From 4aa2ae61ebf82dc97c5f9c63dc2feb7cce6251f0 Mon Sep 17 00:00:00 2001
From: Andre Stenvall <andre@stenvall.me>
Date: Tue, 5 Dec 2017 13:44:24 +0100
Subject: [PATCH 01/12] Added viewReuseGroup to layouts

---
 Sources/Layout.swift                 | 8 ++++++++
 Sources/Layouts/BaseLayout.swift     | 7 ++++++-
 Sources/Layouts/InsetLayout.swift    | 3 ++-
 Sources/Layouts/LabelLayout.swift    | 3 ++-
 Sources/Layouts/SizeLayout.swift     | 3 ++-
 Sources/Layouts/StackLayout.swift    | 3 ++-
 Sources/Layouts/TextViewLayout.swift | 3 ++-
 Sources/Views/StackView.swift        | 1 +
 8 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/Sources/Layout.swift b/Sources/Layout.swift
index c4a0af00..9aae9674 100644
--- a/Sources/Layout.swift
+++ b/Sources/Layout.swift
@@ -105,6 +105,14 @@ public protocol Layout {
      then that view will be reused for the new layout. If there is more than one view with the same viewReuseId, then an arbitrary one will be reused.
      */
     var viewReuseId: String? { get }
+
+
+    /**
+     An identifier that specifies the type view content
+
+     Use this identifier enable view reuse between layouts that produce same kind of views.
+    */
+    var viewReuseGroup: String? { get }
 }
 
 public extension Layout {
diff --git a/Sources/Layouts/BaseLayout.swift b/Sources/Layouts/BaseLayout.swift
index e4fc5b09..014ac2a4 100644
--- a/Sources/Layouts/BaseLayout.swift
+++ b/Sources/Layouts/BaseLayout.swift
@@ -23,6 +23,10 @@ open class BaseLayout<V: View> {
     /// It is used to identify which views should be reused when animating from one layout to another.
     open let viewReuseId: String?
 
+    /// An identifier for layouts that produce same view
+    /// It is used to identify if view can be reused for another layout
+    open let viewReuseGroup: String?
+
     /// A configuration block that is run on the main thread after the view is created.
     open let config: ((V) -> Void)?
 
@@ -30,10 +34,11 @@ open class BaseLayout<V: View> {
         return config != nil
     }
 
-    public init(alignment: Alignment, flexibility: Flexibility, viewReuseId: String? = nil, config: ((V) -> Void)?) {
+    public init(alignment: Alignment, flexibility: Flexibility, viewReuseId: String? = nil, viewReuseGroup: String? = nil, config: ((V) -> Void)?) {
         self.alignment = alignment
         self.flexibility = flexibility
         self.viewReuseId = viewReuseId
+        self.viewReuseGroup = viewReuseGroup
         self.config = config
     }
 
diff --git a/Sources/Layouts/InsetLayout.swift b/Sources/Layouts/InsetLayout.swift
index bf92a13a..493a4455 100644
--- a/Sources/Layouts/InsetLayout.swift
+++ b/Sources/Layouts/InsetLayout.swift
@@ -20,11 +20,12 @@ open class InsetLayout<V: View>: BaseLayout<V>, ConfigurableLayout {
     public init(insets: EdgeInsets,
                 alignment: Alignment = Alignment.fill,
                 viewReuseId: String? = nil,
+                viewReuseGroup: String? = nil,
                 sublayout: Layout,
                 config: ((V) -> Void)? = nil) {
         self.insets = insets
         self.sublayout = sublayout
-        super.init(alignment: alignment, flexibility: sublayout.flexibility, viewReuseId: viewReuseId, config: config)
+        super.init(alignment: alignment, flexibility: sublayout.flexibility, viewReuseId: viewReuseId, viewReuseGroup: viewReuseGroup, config: config)
     }
 
     public convenience init(inset: CGFloat,
diff --git a/Sources/Layouts/LabelLayout.swift b/Sources/Layouts/LabelLayout.swift
index b1fa4ccb..ceaae167 100644
--- a/Sources/Layouts/LabelLayout.swift
+++ b/Sources/Layouts/LabelLayout.swift
@@ -23,12 +23,13 @@ open class LabelLayout<Label: UILabel>: BaseLayout<Label>, ConfigurableLayout {
                 alignment: Alignment = LabelLayoutDefaults.defaultAlignment,
                 flexibility: Flexibility = LabelLayoutDefaults.defaultFlexibility,
                 viewReuseId: String? = nil,
+                viewReuseGroup: String? = nil,
                 config: ((Label) -> Void)? = nil) {
         
         self.text = text
         self.numberOfLines = numberOfLines
         self.font = font
-        super.init(alignment: alignment, flexibility: flexibility, viewReuseId: viewReuseId, config: config)
+        super.init(alignment: alignment, flexibility: flexibility, viewReuseId: viewReuseId, viewReuseGroup: viewReuseGroup, config: config)
     }
 
     // MARK: - Convenience initializers
diff --git a/Sources/Layouts/SizeLayout.swift b/Sources/Layouts/SizeLayout.swift
index 49acb27f..959ac906 100644
--- a/Sources/Layouts/SizeLayout.swift
+++ b/Sources/Layouts/SizeLayout.swift
@@ -62,6 +62,7 @@ open class SizeLayout<V: View>: BaseLayout<V>, ConfigurableLayout {
                 alignment: Alignment? = nil,
                 flexibility: Flexibility? = nil,
                 viewReuseId: String? = nil,
+                viewReuseGroup: String? = nil,
                 sublayout: Layout? = nil,
                 config: ((V) -> Void)? = nil) {
 
@@ -75,7 +76,7 @@ open class SizeLayout<V: View>: BaseLayout<V>, ConfigurableLayout {
                                                                        maxWidth: maxWidth,
                                                                        minHeight: minHeight,
                                                                        maxHeight: maxHeight)
-        super.init(alignment: alignment, flexibility: flexibility, viewReuseId: viewReuseId, config: config)
+        super.init(alignment: alignment, flexibility: flexibility, viewReuseId: viewReuseId, viewReuseGroup: viewReuseGroup, config: config)
     }
 
     // MARK: - Convenience initializers
diff --git a/Sources/Layouts/StackLayout.swift b/Sources/Layouts/StackLayout.swift
index 558e582b..75f4dd6b 100644
--- a/Sources/Layouts/StackLayout.swift
+++ b/Sources/Layouts/StackLayout.swift
@@ -39,6 +39,7 @@ open class StackLayout<V: View>: BaseLayout<V> {
                 alignment: Alignment = .fill,
                 flexibility: Flexibility? = nil,
                 viewReuseId: String? = nil,
+                viewReuseGroup: String? = nil,
                 sublayouts: [Layout],
                 config: ((V) -> Void)? = nil) {
         
@@ -47,7 +48,7 @@ open class StackLayout<V: View>: BaseLayout<V> {
         self.distribution = distribution
         self.sublayouts = sublayouts
         let flexibility = flexibility ?? StackLayout.defaultFlexibility(axis: axis, sublayouts: sublayouts)
-        super.init(alignment: alignment, flexibility: flexibility, viewReuseId: viewReuseId, config: config)
+        super.init(alignment: alignment, flexibility: flexibility, viewReuseId: viewReuseId, viewReuseGroup: viewReuseGroup, config: config)
     }
 }
 
diff --git a/Sources/Layouts/TextViewLayout.swift b/Sources/Layouts/TextViewLayout.swift
index 5e184b95..b689d029 100644
--- a/Sources/Layouts/TextViewLayout.swift
+++ b/Sources/Layouts/TextViewLayout.swift
@@ -34,6 +34,7 @@ open class TextViewLayout<TextView: UITextView>: BaseLayout<TextView>, Configura
                 layoutAlignment: Alignment = TextViewLayoutDefaults.defaultAlignment,
                 flexibility: Flexibility = TextViewLayoutDefaults.defaultFlexibility,
                 viewReuseId: String? = nil,
+                viewReuseGroup: String? = nil,
                 config: ((TextView) -> Void)? = nil) {
         self.text = text
         self.font = font
@@ -47,7 +48,7 @@ open class TextViewLayout<TextView: UITextView>: BaseLayout<TextView>, Configura
             self.isTextEmpty = text.isEmpty
         }
 
-        super.init(alignment: layoutAlignment, flexibility: flexibility, viewReuseId: viewReuseId, config: config)
+        super.init(alignment: layoutAlignment, flexibility: flexibility, viewReuseId: viewReuseId, viewReuseGroup: viewReuseGroup, config: config)
     }
 
     // MARK: - Convenience initializers
diff --git a/Sources/Views/StackView.swift b/Sources/Views/StackView.swift
index 5a2fa14b..c6bef9c2 100644
--- a/Sources/Views/StackView.swift
+++ b/Sources/Views/StackView.swift
@@ -130,6 +130,7 @@ private struct ViewLayout: ConfigurableLayout {
     let needsView = true
     let view: UIView
     let viewReuseId: String? = nil
+    let viewReuseGroup: String? = nil
 
     func measurement(within maxSize: CGSize) -> LayoutMeasurement {
         let size = view.sizeThatFits(maxSize)

From c8cc3ee3a8a83ab82eee683c189ed5f876ff8de6 Mon Sep 17 00:00:00 2001
From: Andre Stenvall <andre@stenvall.me>
Date: Tue, 5 Dec 2017 15:38:12 +0100
Subject: [PATCH 02/12] Add ViewRecyclerViewStorage

---
 LayoutKit.xcodeproj/project.pbxproj           | 16 ++++
 .../ViewRecyclerViewStorageTests.swift        | 87 +++++++++++++++++++
 Sources/ViewRecyclerViewStorage.swift         | 44 ++++++++++
 3 files changed, 147 insertions(+)
 create mode 100644 LayoutKitTests/ViewRecyclerViewStorageTests.swift
 create mode 100644 Sources/ViewRecyclerViewStorage.swift

diff --git a/LayoutKit.xcodeproj/project.pbxproj b/LayoutKit.xcodeproj/project.pbxproj
index 443b862d..ece45649 100644
--- a/LayoutKit.xcodeproj/project.pbxproj
+++ b/LayoutKit.xcodeproj/project.pbxproj
@@ -201,6 +201,12 @@
 		0BD5F82C1DB43F9B00108688 /* ButtonLayoutTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 0BD5F82B1DB43F9B00108688 /* ButtonLayoutTests.swift */; };
 		0BDDF95B1E25ACCE008B0A6F /* ReloadableViewTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 0BDDF95A1E25ACCE008B0A6F /* ReloadableViewTests.swift */; };
 		0BDDF95C1E25ACCE008B0A6F /* ReloadableViewTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 0BDDF95A1E25ACCE008B0A6F /* ReloadableViewTests.swift */; };
+		3F387DFE1FD6D9210045475D /* ViewRecyclerViewStorage.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3F387DFD1FD6D9210045475D /* ViewRecyclerViewStorage.swift */; };
+		3F387DFF1FD6D9210045475D /* ViewRecyclerViewStorage.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3F387DFD1FD6D9210045475D /* ViewRecyclerViewStorage.swift */; };
+		3F387E001FD6D9210045475D /* ViewRecyclerViewStorage.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3F387DFD1FD6D9210045475D /* ViewRecyclerViewStorage.swift */; };
+		3F387E021FD6D9D20045475D /* ViewRecyclerViewStorageTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3F387E011FD6D9D20045475D /* ViewRecyclerViewStorageTests.swift */; };
+		3F387E031FD6D9D20045475D /* ViewRecyclerViewStorageTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3F387E011FD6D9D20045475D /* ViewRecyclerViewStorageTests.swift */; };
+		3F387E041FD6D9D20045475D /* ViewRecyclerViewStorageTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3F387E011FD6D9D20045475D /* ViewRecyclerViewStorageTests.swift */; };
 		4468A31D1E46460B00341D07 /* NSAttributedStringExtension.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4468A31C1E46460B00341D07 /* NSAttributedStringExtension.swift */; };
 		4468A31E1E464A3900341D07 /* NSAttributedStringExtension.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4468A31C1E46460B00341D07 /* NSAttributedStringExtension.swift */; };
 		448CEC0F1E4E0CB500F8AD9E /* TextViewDefaultFont.swift in Sources */ = {isa = PBXBuildFile; fileRef = 448CEC0E1E4E0CB500F8AD9E /* TextViewDefaultFont.swift */; };
@@ -391,6 +397,8 @@
 		0BD5F8281DB43B4500108688 /* ButtonLayout.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ButtonLayout.swift; sourceTree = "<group>"; };
 		0BD5F82B1DB43F9B00108688 /* ButtonLayoutTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ButtonLayoutTests.swift; sourceTree = "<group>"; };
 		0BDDF95A1E25ACCE008B0A6F /* ReloadableViewTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ReloadableViewTests.swift; sourceTree = "<group>"; };
+		3F387DFD1FD6D9210045475D /* ViewRecyclerViewStorage.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ViewRecyclerViewStorage.swift; sourceTree = "<group>"; };
+		3F387E011FD6D9D20045475D /* ViewRecyclerViewStorageTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ViewRecyclerViewStorageTests.swift; sourceTree = "<group>"; };
 		4468A31C1E46460B00341D07 /* NSAttributedStringExtension.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = NSAttributedStringExtension.swift; sourceTree = "<group>"; };
 		448CEC0E1E4E0CB500F8AD9E /* TextViewDefaultFont.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = TextViewDefaultFont.swift; sourceTree = "<group>"; };
 		44F968141E425F5D00392763 /* TextViewLayout.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = TextViewLayout.swift; sourceTree = "<group>"; };
@@ -559,6 +567,7 @@
 				0BD42BDB1DB5EAAD00E04AA3 /* Text.swift */,
 				0BCB75EA1D8724800065E02A /* UIKitSupport.swift */,
 				0BCB75EB1D8724800065E02A /* ViewRecycler.swift */,
+				3F387DFD1FD6D9210045475D /* ViewRecyclerViewStorage.swift */,
 				0BCB75EC1D8724800065E02A /* Views */,
 			);
 			name = LayoutKit;
@@ -598,6 +607,7 @@
 				44F968161E42639500392763 /* TextViewLayoutTests.swift */,
 				0BCB76671D8725310065E02A /* UIFontExtension.swift */,
 				0BCB76681D8725310065E02A /* ViewRecyclerTests.swift */,
+				3F387E011FD6D9D20045475D /* ViewRecyclerViewStorageTests.swift */,
 			);
 			path = LayoutKitTests;
 			sourceTree = "<group>";
@@ -1039,6 +1049,7 @@
 				0BCB760C1D8724800065E02A /* LayoutAdapterCollectionView.swift in Sources */,
 				0BD5F8291DB43B4500108688 /* ButtonLayout.swift in Sources */,
 				0BCB76001D8724800065E02A /* LayoutMeasurement.swift in Sources */,
+				3F387DFE1FD6D9210045475D /* ViewRecyclerViewStorage.swift in Sources */,
 				0BCB76021D8724800065E02A /* InsetLayout.swift in Sources */,
 				0BCB76061D8724800065E02A /* AxisFlexibility.swift in Sources */,
 				448CEC0F1E4E0CB500F8AD9E /* TextViewDefaultFont.swift in Sources */,
@@ -1086,6 +1097,7 @@
 				0B2D09381D872F75007E487C /* ViewRecyclerTests.swift in Sources */,
 				0B2D09341D872F75007E487C /* StackViewTests.swift in Sources */,
 				0B2D09281D872F75007E487C /* LabelLayoutTests.swift in Sources */,
+				3F387E021FD6D9D20045475D /* ViewRecyclerViewStorageTests.swift in Sources */,
 				0B2D09231D872F75007E487C /* AlignmentTests.swift in Sources */,
 				0B2D09261D872F75007E487C /* DensityAssertions.swift in Sources */,
 				0BD5F82C1DB43F9B00108688 /* ButtonLayoutTests.swift in Sources */,
@@ -1118,6 +1130,7 @@
 				0BCB76301D8724C70065E02A /* LayoutMeasurement.swift in Sources */,
 				0B193BBA1D888B6300FCA22D /* IndexSetExtension.swift in Sources */,
 				0BCB76371D8724CA0065E02A /* InsetLayout.swift in Sources */,
+				3F387DFF1FD6D9210045475D /* ViewRecyclerViewStorage.swift in Sources */,
 				0BCB76401D8724CF0065E02A /* AxisFlexibility.swift in Sources */,
 				0BCB762C1D8724C70065E02A /* CGSizeExtension.swift in Sources */,
 				0BCB76361D8724CA0065E02A /* BaseLayout.swift in Sources */,
@@ -1153,6 +1166,7 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				3F387E031FD6D9D20045475D /* ViewRecyclerViewStorageTests.swift in Sources */,
 				0B765F311DC135B8000BF1FD /* CGFloatExtensionTests.swift in Sources */,
 				0B2D09421D872F75007E487C /* ReloadableViewLayoutAdapterCollectionViewTests.swift in Sources */,
 				0B2D09441D872F75007E487C /* ReloadableViewLayoutAdapterTestCase.swift in Sources */,
@@ -1191,6 +1205,7 @@
 				0BCB761B1D8724C10065E02A /* Animation.swift in Sources */,
 				0BCB76471D8724D00065E02A /* AxisSize.swift in Sources */,
 				0BCB76351D8724C70065E02A /* LayoutMeasurement.swift in Sources */,
+				3F387E001FD6D9210045475D /* ViewRecyclerViewStorage.swift in Sources */,
 				0BCB763C1D8724CB0065E02A /* InsetLayout.swift in Sources */,
 				0B193BBB1D888B6400FCA22D /* IndexSetExtension.swift in Sources */,
 				0B193BBD1D888B6D00FCA22D /* CollectionExtension.swift in Sources */,
@@ -1214,6 +1229,7 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				3F387E041FD6D9D20045475D /* ViewRecyclerViewStorageTests.swift in Sources */,
 				0B2D095E1D872F76007E487C /* StackLayoutSpacingTests.swift in Sources */,
 				0B2D09641D872F76007E487C /* ViewRecyclerTests.swift in Sources */,
 				0B2D094F1D872F76007E487C /* AlignmentTests.swift in Sources */,
diff --git a/LayoutKitTests/ViewRecyclerViewStorageTests.swift b/LayoutKitTests/ViewRecyclerViewStorageTests.swift
new file mode 100644
index 00000000..133bbb91
--- /dev/null
+++ b/LayoutKitTests/ViewRecyclerViewStorageTests.swift
@@ -0,0 +1,87 @@
+// Copyright 2016 LinkedIn Corp.
+// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+
+import XCTest
+@testable import LayoutKit
+
+class ViewRecyclerViewStorageTests: XCTestCase {
+
+    func testViewWithReuseId_viewWithReuseIdExists_shouldReturnView() {
+        let view1 = View(viewReuseId: "1")
+        let view2 = View(viewReuseId: "2")
+        let storage = ViewRecyclerViewStorage()
+        storage.add(view: view1)
+        storage.add(view: view2)
+
+        let v = storage.popView(withReuseId: "2")
+        XCTAssertEqual(view2, v)
+    }
+
+    func testViewWithReuseId_viewWithReuseIdExists_shouldNotBeAbleToPopSameViewTwice() {
+        let view1 = View(viewReuseId: "1")
+        let view2 = View(viewReuseId: "2")
+        let storage = ViewRecyclerViewStorage()
+        storage.add(view: view1)
+        storage.add(view: view2)
+
+        XCTAssertEqual(storage.popView(withReuseId: "2"), view2)
+        XCTAssertNil(storage.popView(withReuseId: "2"), "View should already been popped")
+    }
+
+    func testViewWithReuseGroup_viewWithReuseGroupMultipleMatches_shouldKeepReturningViewsMatchingGroup() {
+        let view1 = View(viewReuseId: "1", viewReuseGroup: "group1")
+        let view2 = View(viewReuseId: "2", viewReuseGroup: "group1")
+        let storage = ViewRecyclerViewStorage()
+        storage.add(view: view1)
+        storage.add(view: view2)
+
+        XCTAssertEqual(storage.popView(withReuseGroup: "group1"), view1)
+        XCTAssertEqual(storage.popView(withReuseGroup: "group1"), view2)
+        XCTAssertNil(storage.popView(withReuseGroup: "group1"))
+    }
+
+    func testViewWithReuseGroup_viewWithReuseGroupMatch_shouldNotBeAbleToRetrieveThatViewAgain() {
+        let view1 = View(viewReuseId: "1", viewReuseGroup: "group1")
+        let view2 = View(viewReuseId: "2", viewReuseGroup: "group1")
+        let storage = ViewRecyclerViewStorage()
+        storage.add(view: view1)
+        storage.add(view: view2)
+
+        XCTAssertEqual(storage.popView(withReuseGroup: "group1"), view1)
+        XCTAssertNil(storage.popView(withReuseId: "1"), "View should already been popped")
+    }
+
+    func testRemoveView() {
+        let view1 = View(viewReuseId: "1")
+        let view2 = View(viewReuseId: "2")
+        let view3 = View(viewReuseId: "3", viewReuseGroup: "group")
+        let storage = ViewRecyclerViewStorage()
+        storage.add(view: view1)
+        storage.add(view: view2)
+        storage.add(view: view3)
+
+        storage.remove(view: view2)
+        XCTAssertNil(storage.popView(withReuseId: "2"), "View should have been removed")
+    }
+
+    func testRemoveAll_viewReuseIds() {
+        let view1 = View(viewReuseId: "1")
+        let view2 = View(viewReuseId: "2")
+        let view3 = View(viewReuseId: "3", viewReuseGroup: "group")
+        let storage = ViewRecyclerViewStorage()
+        storage.add(view: view1)
+        storage.add(view: view2)
+        storage.add(view: view3)
+
+        storage.removeAll()
+
+        XCTAssertNil(storage.popView(withReuseId: "1"), "View should have been removed")
+        XCTAssertNil(storage.popView(withReuseId: "2"), "View should have been removed")
+        XCTAssertNil(storage.popView(withReuseGroup: "group"), "View should have been removed")
+    }
+}
diff --git a/Sources/ViewRecyclerViewStorage.swift b/Sources/ViewRecyclerViewStorage.swift
new file mode 100644
index 00000000..0ef8a5b1
--- /dev/null
+++ b/Sources/ViewRecyclerViewStorage.swift
@@ -0,0 +1,44 @@
+// Copyright 2016 LinkedIn Corp.
+// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+
+import Foundation
+
+class ViewRecyclerViewStorage {
+
+    private var views: [View] = []
+
+    func add(view: View) {
+        self.views.append(view)
+    }
+
+    func popView(withReuseId viewId: String) -> View? {
+        let index = self.views.index { $0.viewReuseId == viewId }
+        guard let viewIndex = index else { return nil }
+        return self.views.remove(at: viewIndex)
+    }
+
+    func popView(withReuseGroup viewGroup: String) -> View? {
+        let index = self.views.index { $0.viewReuseGroup == viewGroup }
+        guard let viewIndex = index else { return nil }
+        return self.views.remove(at: viewIndex)
+    }
+
+    func foreach(_ closure: (View) -> Void) {
+        self.views.forEach(closure)
+    }
+
+    func remove(view: View) {
+        if let index = self.views.index(where: { $0 == view }) {
+            self.views.remove(at: index)
+        }
+    }
+
+    func removeAll() {
+        self.views.removeAll()
+    }
+}

From bd737a7875c626158e91adb81be61db9043083c2 Mon Sep 17 00:00:00 2001
From: Andre Stenvall <andre@stenvall.me>
Date: Wed, 6 Dec 2017 09:53:49 +0100
Subject: [PATCH 03/12] Add support for viewReuseGroup in ViewRecycler

---
 LayoutKitTests/ViewRecyclerTests.swift | 51 +++++++++++++++++++++---
 Sources/LayoutArrangement.swift        |  2 +-
 Sources/ViewRecycler.swift             | 54 +++++++++++++-------------
 Sources/ViewRecyclerViewStorage.swift  | 11 +++++-
 4 files changed, 82 insertions(+), 36 deletions(-)

diff --git a/LayoutKitTests/ViewRecyclerTests.swift b/LayoutKitTests/ViewRecyclerTests.swift
index 5f4e4541..a1931b1b 100644
--- a/LayoutKitTests/ViewRecyclerTests.swift
+++ b/LayoutKitTests/ViewRecyclerTests.swift
@@ -19,7 +19,7 @@ class ViewRecyclerTests: XCTestCase {
 
         let recycler = ViewRecycler(rootView: root)
         let expectedView = View()
-        let v: View? = recycler.makeOrRecycleView(havingViewReuseId: nil, viewProvider: {
+        let v: View? = recycler.makeOrRecycleView(havingViewReuseId: nil, orViewReuseGroup: nil, viewProvider: {
             return expectedView
         })
         XCTAssertEqual(v, expectedView)
@@ -36,7 +36,7 @@ class ViewRecyclerTests: XCTestCase {
 
         let recycler = ViewRecycler(rootView: root)
         let expectedView = View()
-        let v: View? = recycler.makeOrRecycleView(havingViewReuseId: nil, viewProvider: {
+        let v: View? = recycler.makeOrRecycleView(havingViewReuseId: nil, orViewReuseGroup: nil, viewProvider: {
             return expectedView
         })
         XCTAssertEqual(v, expectedView)
@@ -51,7 +51,7 @@ class ViewRecyclerTests: XCTestCase {
         root.addSubview(one)
 
         let recycler = ViewRecycler(rootView: root)
-        let v: View? = recycler.makeOrRecycleView(havingViewReuseId: "1", viewProvider: {
+        let v: View? = recycler.makeOrRecycleView(havingViewReuseId: "1", orViewReuseGroup: nil, viewProvider: {
             XCTFail("view should have been recycled")
             return View()
         })
@@ -67,7 +67,7 @@ class ViewRecyclerTests: XCTestCase {
         root.addSubview(one)
 
         let recycler = ViewRecycler(rootView: root)
-        let v: View? = recycler.makeOrRecycleView(havingViewReuseId: nil, viewProvider: {
+        let v: View? = recycler.makeOrRecycleView(havingViewReuseId: nil, orViewReuseGroup: nil, viewProvider: {
             return one
         })
         XCTAssertEqual(v, one)
@@ -82,7 +82,7 @@ class ViewRecyclerTests: XCTestCase {
         root.addSubview(one)
 
         let recycler = ViewRecycler(rootView: root)
-        let v: View? = recycler.makeOrRecycleView(havingViewReuseId: nil, viewProvider: {
+        let v: View? = recycler.makeOrRecycleView(havingViewReuseId: nil, orViewReuseGroup: nil, viewProvider: {
             return one
         })
         XCTAssertEqual(v, one)
@@ -91,6 +91,22 @@ class ViewRecyclerTests: XCTestCase {
         XCTAssertNotNil(one.superview)
     }
 
+    func testViewProviderViewCreationShouldSetViewIdentifiers() {
+        let root = View()
+        let oldView = View()
+        root.addSubview(oldView)
+
+        let newView = View()
+
+        let recycler = ViewRecycler(rootView: root)
+        let v: View? = recycler.makeOrRecycleView(havingViewReuseId: "2", orViewReuseGroup: "group2", viewProvider: {
+            return newView
+        })
+        XCTAssertEqual(v, newView)
+        XCTAssertEqual(newView.viewReuseId, "2")
+        XCTAssertEqual(newView.viewReuseGroup, "group2")
+    }
+
     /// Test for safe subview-purge in composite view e.g. UIButton.
     /// - SeeAlso: https://github.com/linkedin/LayoutKit/pull/85
     #if os(iOS) || os(tvOS)
@@ -104,7 +120,7 @@ class ViewRecyclerTests: XCTestCase {
         XCTAssertEqual(button.subviews.count, 1, "UIButton should have 1 subview because `title` is set")
 
         let recycler = ViewRecycler(rootView: root)
-        let v: View? = recycler.makeOrRecycleView(havingViewReuseId: "1", viewProvider: {
+        let v: View? = recycler.makeOrRecycleView(havingViewReuseId: "1", orViewReuseGroup: nil, viewProvider: {
             XCTFail("button should have been recycled")
             return View()
         })
@@ -116,6 +132,23 @@ class ViewRecyclerTests: XCTestCase {
         XCTAssertEqual(button.subviews.count, 1, "UIButton's subviews should not be removed by `recycler`")
     }
     #endif
+
+    func testRecycledFromViewGroup() {
+        let root = View()
+        let one = View(viewReuseId: "1", viewReuseGroup: "view")
+        root.addSubview(one)
+
+        let recycler = ViewRecycler(rootView: root)
+        let v: View? = recycler.makeOrRecycleView(havingViewReuseId: "2", orViewReuseGroup: "view", viewProvider: {
+            XCTFail("view should have been recycled")
+            return View()
+        })
+        XCTAssertEqual(v, one)
+
+        recycler.purgeViews()
+        XCTAssertNotNil(one.superview)
+    }
+
 }
 
 extension View {
@@ -123,4 +156,10 @@ extension View {
         self.init(frame: .zero)
         self.viewReuseId = viewReuseId
     }
+
+    convenience init(viewReuseId: String?, viewReuseGroup: String?) {
+        self.init(frame: .zero)
+        self.viewReuseId = viewReuseId
+        self.viewReuseGroup = viewReuseGroup
+    }
 }
diff --git a/Sources/LayoutArrangement.swift b/Sources/LayoutArrangement.swift
index 94289741..2bcacfde 100644
--- a/Sources/LayoutArrangement.swift
+++ b/Sources/LayoutArrangement.swift
@@ -119,7 +119,7 @@ public struct LayoutArrangement {
             return sublayout.makeSubviews(from: recycler, prepareAnimation: prepareAnimation)
         })
         // If we are preparing an animation, then we don't want to update frames or configure views.
-        if layout.needsView, let view = recycler.makeOrRecycleView(havingViewReuseId: layout.viewReuseId, viewProvider: layout.makeView) {
+        if layout.needsView, let view = recycler.makeOrRecycleView(havingViewReuseId: layout.viewReuseId, orViewReuseGroup: layout.viewReuseGroup, viewProvider: layout.makeView) {
             if !prepareAnimation {
                 view.frame = frame
                 layout.configure(baseTypeView: view)
diff --git a/Sources/ViewRecycler.swift b/Sources/ViewRecycler.swift
index d3edca10..71e06bd0 100644
--- a/Sources/ViewRecycler.swift
+++ b/Sources/ViewRecycler.swift
@@ -17,16 +17,15 @@ import ObjectiveC
  */
 class ViewRecycler {
 
-    private var viewsById = [String: View]()
-    private var unidentifiedViews = Set<View>()
+    private var viewStorage = ViewRecyclerViewStorage()
 
     /// Retains all subviews of rootView for recycling.
     init(rootView: View?) {
-        rootView?.walkSubviews { (view) in
-            if let viewReuseId = view.viewReuseId {
-                self.viewsById[viewReuseId] = view
-            } else {
-                self.unidentifiedViews.insert(view)
+        rootView?.walkSubviews { view in
+            self.viewStorage.add(view: view)
+
+            if view.isLayoutKitView {
+                view.removeFromSuperview()
             }
         }
     }
@@ -35,41 +34,32 @@ class ViewRecycler {
      Returns a view for the layout.
      It may recycle an existing view or create a new view.
      */
-    func makeOrRecycleView(havingViewReuseId viewReuseId: String?, viewProvider: () -> View) -> View? {
+    func makeOrRecycleView(havingViewReuseId viewReuseId: String?, orViewReuseGroup viewReuseGroup: String?, viewProvider: () -> View) -> View? {
+
         // If we have a recyclable view that matches type and id, then reuse it.
-        if let viewReuseId = viewReuseId, let view = viewsById[viewReuseId] {
-            viewsById[viewReuseId] = nil
+        if let viewReuseId = viewReuseId, let view = self.viewStorage.popView(withReuseId: viewReuseId) {
+            return view
+        }
+        if let viewGroup = viewReuseGroup, let view = self.viewStorage.popView(withReuseGroup: viewGroup) {
             return view
         }
 
         let providedView = viewProvider()
         providedView.isLayoutKitView = true
-
-        // Remove the provided view from the list of cached views.
-        if let viewReuseId = providedView.viewReuseId, let oldView = viewsById[viewReuseId], oldView == providedView {
-            viewsById[viewReuseId] = nil
-        } else {
-            unidentifiedViews.remove(providedView)
-        }
         providedView.viewReuseId = viewReuseId
+        providedView.viewReuseGroup = viewReuseGroup
+        self.viewStorage.remove(view: providedView)
         return providedView
     }
 
-    /// Removes all unrecycled views from the view hierarchy.
+    /// Removes all unrecycled views
     func purgeViews() {
-        for view in viewsById.values {
-            view.removeFromSuperview()
-        }
-        viewsById.removeAll()
-
-        for view in unidentifiedViews where view.isLayoutKitView {
-            view.removeFromSuperview()
-        }
-        unidentifiedViews.removeAll()
+        self.viewStorage.removeAll()
     }
 }
 
 private var viewReuseIdKey: UInt8 = 0
+private var viewReuseGroupKey: UInt8 = 0
 private var isLayoutKitViewKey: UInt8 = 0
 
 extension View {
@@ -92,6 +82,16 @@ extension View {
         }
     }
 
+    // Identifies the reuseg roup this view belongs to
+    public internal(set) var viewReuseGroup: String? {
+        get {
+            return objc_getAssociatedObject(self, &viewReuseGroupKey) as? String
+        }
+        set {
+            objc_setAssociatedObject(self, &viewReuseGroupKey, newValue, .OBJC_ASSOCIATION_RETAIN)
+        }
+    }
+
     /// Indicates the view is managed by LayoutKit that can be safely removed.
     var isLayoutKitView: Bool {
         get {
diff --git a/Sources/ViewRecyclerViewStorage.swift b/Sources/ViewRecyclerViewStorage.swift
index 0ef8a5b1..0f93d11e 100644
--- a/Sources/ViewRecyclerViewStorage.swift
+++ b/Sources/ViewRecyclerViewStorage.swift
@@ -10,10 +10,10 @@ import Foundation
 
 class ViewRecyclerViewStorage {
 
-    private var views: [View] = []
+    private var views: Set<View> = []
 
     func add(view: View) {
-        self.views.append(view)
+        self.views.insert(view)
     }
 
     func popView(withReuseId viewId: String) -> View? {
@@ -42,3 +42,10 @@ class ViewRecyclerViewStorage {
         self.views.removeAll()
     }
 }
+
+extension ViewRecyclerViewStorage : CustomDebugStringConvertible {
+
+    var debugDescription: String {
+        return "\(type(of: self)) - \(self.views)"
+    }
+}

From e20eda96ff840b6fa613e31f7e6385821e0cdf85 Mon Sep 17 00:00:00 2001
From: Andre Stenvall <andre@stenvall.me>
Date: Wed, 6 Dec 2017 10:05:01 +0100
Subject: [PATCH 04/12] Refactor ViewRecyclerViewStorage

---
 Sources/ViewRecyclerViewStorage.swift | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/Sources/ViewRecyclerViewStorage.swift b/Sources/ViewRecyclerViewStorage.swift
index 0f93d11e..10694e2e 100644
--- a/Sources/ViewRecyclerViewStorage.swift
+++ b/Sources/ViewRecyclerViewStorage.swift
@@ -17,15 +17,17 @@ class ViewRecyclerViewStorage {
     }
 
     func popView(withReuseId viewId: String) -> View? {
-        let index = self.views.index { $0.viewReuseId == viewId }
-        guard let viewIndex = index else { return nil }
-        return self.views.remove(at: viewIndex)
+        guard let index = self.views.index(where: { $0.viewReuseId == viewId }) else {
+            return nil
+        }
+        return self.views.remove(at: index)
     }
 
     func popView(withReuseGroup viewGroup: String) -> View? {
-        let index = self.views.index { $0.viewReuseGroup == viewGroup }
-        guard let viewIndex = index else { return nil }
-        return self.views.remove(at: viewIndex)
+        guard let index = self.views.index(where: { $0.viewReuseGroup == viewGroup }) else {
+            return nil
+        }
+        return self.views.remove(at: index)
     }
 
     func foreach(_ closure: (View) -> Void) {

From 8378852c34000b84be684f9a72eb6de0989e4774 Mon Sep 17 00:00:00 2001
From: Andre Stenvall <andre@stenvall.me>
Date: Wed, 6 Dec 2017 10:34:33 +0100
Subject: [PATCH 05/12] Add missing viewReuseGroup to LabelLayout and
 SizeLayout

---
 Sources/Layouts/LabelLayout.swift |  4 ++++
 Sources/Layouts/SizeLayout.swift  | 12 ++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/Sources/Layouts/LabelLayout.swift b/Sources/Layouts/LabelLayout.swift
index ceaae167..9d23ed5b 100644
--- a/Sources/Layouts/LabelLayout.swift
+++ b/Sources/Layouts/LabelLayout.swift
@@ -40,6 +40,7 @@ open class LabelLayout<Label: UILabel>: BaseLayout<Label>, ConfigurableLayout {
                             alignment: Alignment = LabelLayoutDefaults.defaultAlignment,
                             flexibility: Flexibility = LabelLayoutDefaults.defaultFlexibility,
                             viewReuseId: String? = nil,
+                            viewReuseGroup: String? = nil,
                             config: ((Label) -> Void)? = nil) {
 
         self.init(text: .unattributed(text),
@@ -48,6 +49,7 @@ open class LabelLayout<Label: UILabel>: BaseLayout<Label>, ConfigurableLayout {
                   alignment: alignment,
                   flexibility: flexibility,
                   viewReuseId: viewReuseId,
+                  viewReuseGroup: viewReuseGroup,
                   config: config)
     }
 
@@ -57,6 +59,7 @@ open class LabelLayout<Label: UILabel>: BaseLayout<Label>, ConfigurableLayout {
                             alignment: Alignment = LabelLayoutDefaults.defaultAlignment,
                             flexibility: Flexibility = LabelLayoutDefaults.defaultFlexibility,
                             viewReuseId: String? = nil,
+                            viewReuseGroup: String? = nil,
                             config: ((Label) -> Void)? = nil) {
 
         self.init(text: .attributed(attributedText),
@@ -65,6 +68,7 @@ open class LabelLayout<Label: UILabel>: BaseLayout<Label>, ConfigurableLayout {
                   alignment: alignment,
                   flexibility: flexibility,
                   viewReuseId: viewReuseId,
+                  viewReuseGroup: viewReuseGroup,
                   config: config)
     }
 
diff --git a/Sources/Layouts/SizeLayout.swift b/Sources/Layouts/SizeLayout.swift
index 959ac906..859fd199 100644
--- a/Sources/Layouts/SizeLayout.swift
+++ b/Sources/Layouts/SizeLayout.swift
@@ -88,6 +88,7 @@ open class SizeLayout<V: View>: BaseLayout<V>, ConfigurableLayout {
                             alignment: Alignment? = nil,
                             flexibility: Flexibility? = nil,
                             viewReuseId: String? = nil,
+                            viewReuseGroup: String? = nil,
                             sublayout: Layout? = nil,
                             config: ((V) -> Void)? = nil) {
 
@@ -98,6 +99,7 @@ open class SizeLayout<V: View>: BaseLayout<V>, ConfigurableLayout {
                   alignment: alignment,
                   flexibility: flexibility,
                   viewReuseId: viewReuseId,
+                  viewReuseGroup: viewReuseGroup,
                   sublayout: sublayout,
                   config: config)
     }
@@ -108,6 +110,7 @@ open class SizeLayout<V: View>: BaseLayout<V>, ConfigurableLayout {
                             alignment: Alignment? = nil,
                             flexibility: Flexibility? = nil,
                             viewReuseId: String? = nil,
+                            viewReuseGroup: String? = nil,
                             sublayout: Layout? = nil,
                             config: ((V) -> Void)? = nil) {
 
@@ -118,6 +121,7 @@ open class SizeLayout<V: View>: BaseLayout<V>, ConfigurableLayout {
                   alignment: alignment,
                   flexibility: flexibility,
                   viewReuseId: viewReuseId,
+                  viewReuseGroup: viewReuseGroup,
                   sublayout: sublayout,
                   config: config)
     }
@@ -128,6 +132,7 @@ open class SizeLayout<V: View>: BaseLayout<V>, ConfigurableLayout {
                             alignment: Alignment? = nil,
                             flexibility: Flexibility? = nil,
                             viewReuseId: String? = nil,
+                            viewReuseGroup: String? = nil,
                             sublayout: Layout? = nil,
                             config: ((V) -> Void)? = nil) {
 
@@ -138,6 +143,7 @@ open class SizeLayout<V: View>: BaseLayout<V>, ConfigurableLayout {
                   alignment: alignment,
                   flexibility: flexibility,
                   viewReuseId: viewReuseId,
+                  viewReuseGroup: viewReuseGroup,
                   sublayout: sublayout,
                   config: config)
     }
@@ -146,6 +152,7 @@ open class SizeLayout<V: View>: BaseLayout<V>, ConfigurableLayout {
                             alignment: Alignment? = nil,
                             flexibility: Flexibility? = nil,
                             viewReuseId: String? = nil,
+                            viewReuseGroup: String? = nil,
                             sublayout: Layout? = nil,
                             config: ((V) -> Void)? = nil) {
 
@@ -154,6 +161,7 @@ open class SizeLayout<V: View>: BaseLayout<V>, ConfigurableLayout {
                   alignment: alignment,
                   flexibility: flexibility,
                   viewReuseId: viewReuseId,
+                  viewReuseGroup: viewReuseGroup,
                   sublayout: sublayout,
                   config: config)
     }
@@ -162,6 +170,7 @@ open class SizeLayout<V: View>: BaseLayout<V>, ConfigurableLayout {
                             alignment: Alignment? = nil,
                             flexibility: Flexibility? = nil,
                             viewReuseId: String? = nil,
+                            viewReuseGroup: String? = nil,
                             sublayout: Layout? = nil,
                             config: ((V) -> Void)? = nil) {
 
@@ -170,6 +179,7 @@ open class SizeLayout<V: View>: BaseLayout<V>, ConfigurableLayout {
                   alignment: alignment,
                   flexibility: flexibility,
                   viewReuseId: viewReuseId,
+                  viewReuseGroup: viewReuseGroup,
                   sublayout: sublayout,
                   config: config)
     }
@@ -178,6 +188,7 @@ open class SizeLayout<V: View>: BaseLayout<V>, ConfigurableLayout {
                             alignment: Alignment? = nil,
                             flexibility: Flexibility? = nil,
                             viewReuseId: String? = nil,
+                            viewReuseGroup: String? = nil,
                             sublayout: Layout? = nil,
                             config: ((V) -> Void)? = nil) {
 
@@ -186,6 +197,7 @@ open class SizeLayout<V: View>: BaseLayout<V>, ConfigurableLayout {
                   alignment: alignment,
                   flexibility: flexibility,
                   viewReuseId: viewReuseId,
+                  viewReuseGroup: viewReuseGroup,
                   sublayout: sublayout,
                   config: config)
     }

From 57efea14ae6110208a095bb17bd30eb0853b8fcc Mon Sep 17 00:00:00 2001
From: Andre Stenvall <andre@stenvall.me>
Date: Wed, 6 Dec 2017 12:44:29 +0100
Subject: [PATCH 06/12] Move removeFromSuperview to purge or view reuse

---
 Sources/ViewRecycler.swift | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/Sources/ViewRecycler.swift b/Sources/ViewRecycler.swift
index 71e06bd0..4c24b974 100644
--- a/Sources/ViewRecycler.swift
+++ b/Sources/ViewRecycler.swift
@@ -23,10 +23,6 @@ class ViewRecycler {
     init(rootView: View?) {
         rootView?.walkSubviews { view in
             self.viewStorage.add(view: view)
-
-            if view.isLayoutKitView {
-                view.removeFromSuperview()
-            }
         }
     }
 
@@ -38,9 +34,13 @@ class ViewRecycler {
 
         // If we have a recyclable view that matches type and id, then reuse it.
         if let viewReuseId = viewReuseId, let view = self.viewStorage.popView(withReuseId: viewReuseId) {
+            // Remove from superview to avoid view cycles
+            view.removeFromSuperview()
             return view
         }
         if let viewGroup = viewReuseGroup, let view = self.viewStorage.popView(withReuseGroup: viewGroup) {
+            // Remove from superview to avoid view cycles
+            view.removeFromSuperview()
             return view
         }
 
@@ -54,6 +54,11 @@ class ViewRecycler {
 
     /// Removes all unrecycled views
     func purgeViews() {
+        self.viewStorage.beforeEach { view in
+            if view.isLayoutKitView {
+                view.removeFromSuperview()
+            }
+        }
         self.viewStorage.removeAll()
     }
 }

From f07d1b968b90a88b64accbb809a2236f1b6c06e8 Mon Sep 17 00:00:00 2001
From: Andre Stenvall <andre@stenvall.me>
Date: Wed, 6 Dec 2017 12:44:57 +0100
Subject: [PATCH 07/12] Add final to ViewRecycler and ViewRecyclerViewStorage

---
 Sources/ViewRecycler.swift            | 2 +-
 Sources/ViewRecyclerViewStorage.swift | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/Sources/ViewRecycler.swift b/Sources/ViewRecycler.swift
index 4c24b974..9724e680 100644
--- a/Sources/ViewRecycler.swift
+++ b/Sources/ViewRecycler.swift
@@ -15,7 +15,7 @@ import ObjectiveC
  Call `makeView(layoutId:)` to recycle or create a view of the desired type and id.
  Call `purgeViews()` to remove all unrecycled views from the view hierarchy.
  */
-class ViewRecycler {
+final class ViewRecycler {
 
     private var viewStorage = ViewRecyclerViewStorage()
 
diff --git a/Sources/ViewRecyclerViewStorage.swift b/Sources/ViewRecyclerViewStorage.swift
index 10694e2e..8f00cd7f 100644
--- a/Sources/ViewRecyclerViewStorage.swift
+++ b/Sources/ViewRecyclerViewStorage.swift
@@ -8,7 +8,7 @@
 
 import Foundation
 
-class ViewRecyclerViewStorage {
+final class ViewRecyclerViewStorage {
 
     private var views: Set<View> = []
 

From d70dbceed7b92923de4e50525ae4e1429ae7970e Mon Sep 17 00:00:00 2001
From: Andre Stenvall <andre@stenvall.me>
Date: Wed, 6 Dec 2017 12:48:28 +0100
Subject: [PATCH 08/12] Fix typo

---
 Sources/ViewRecycler.swift | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Sources/ViewRecycler.swift b/Sources/ViewRecycler.swift
index 9724e680..f35d50b9 100644
--- a/Sources/ViewRecycler.swift
+++ b/Sources/ViewRecycler.swift
@@ -54,7 +54,7 @@ final class ViewRecycler {
 
     /// Removes all unrecycled views
     func purgeViews() {
-        self.viewStorage.beforeEach { view in
+        self.viewStorage.foreach { view in
             if view.isLayoutKitView {
                 view.removeFromSuperview()
             }

From 2ef92748fff2dd0d46a9f2b34ab9299151f9ee32 Mon Sep 17 00:00:00 2001
From: Andre Stenvall <andre@stenvall.me>
Date: Tue, 12 Dec 2017 11:11:44 +0100
Subject: [PATCH 09/12] Fix view cycle problem without removing superview on
 reuse

---
 LayoutKitTests/LayoutArrangementTests.swift   | 37 +++++++++++++++++++
 .../ViewRecyclerViewStorageTests.swift        |  6 +--
 Sources/ViewRecycler.swift                    |  4 --
 Sources/ViewRecyclerViewStorage.swift         |  5 ++-
 4 files changed, 43 insertions(+), 9 deletions(-)

diff --git a/LayoutKitTests/LayoutArrangementTests.swift b/LayoutKitTests/LayoutArrangementTests.swift
index 66b42aee..184534ba 100644
--- a/LayoutKitTests/LayoutArrangementTests.swift
+++ b/LayoutKitTests/LayoutArrangementTests.swift
@@ -53,6 +53,43 @@ class LayoutArrangementTests: XCTestCase {
         XCTAssertEqual(container.subviews[2].frame, CGRect(x: 0, y: 30, width: 5, height: 30))
     }
 
+    func testSubViewsSameViewReuseGroup() {
+
+        let forceViewConfig: (View) -> Void = { _ in }
+
+        let leftSubTree = StackLayout(
+            axis: .horizontal,
+            viewReuseGroup: "colorView",
+            sublayouts: [
+                InsetLayout(
+                    insets: UIEdgeInsets(top: 1, left: 1, bottom: 1, right: 1),
+                    viewReuseGroup: "dummy",
+                    sublayout: SizeLayout(width: 5, height: 10, viewReuseGroup: "colorView", config: forceViewConfig),
+                    config: forceViewConfig
+                )
+            ],
+            config: forceViewConfig
+        )
+
+        let right = SizeLayout(width: 5, height: 20, viewReuseGroup: "dummy", config: forceViewConfig)
+        let stack = StackLayout(axis: .vertical, sublayouts: [leftSubTree, right])
+        let container = View()
+
+        // Make sure that we reuse the views in correct order, otherwise we get a view cycle
+        // that will cause a crash.
+        stack.arrangement().makeViews(in: container)
+        XCTAssertEqual(container.subviews.first?.frame, CGRect(x: 0, y: 0, width: 7, height: 12))
+        XCTAssertEqual(container.subviews.first?.subviews.first?.frame, CGRect(x: 0, y: 0, width: 7, height: 12))
+        XCTAssertEqual(container.subviews.first?.subviews.first?.subviews.first?.frame, CGRect(x: 1, y: 1, width: 5, height: 10))
+        XCTAssertEqual(container.subviews.last?.frame, CGRect(x: 1, y: 12, width: 5, height: 20))
+
+        stack.arrangement().makeViews(in: container)
+        XCTAssertEqual(container.subviews.first?.frame, CGRect(x: 0, y: 0, width: 7, height: 12))
+        XCTAssertEqual(container.subviews.first?.subviews.first?.frame, CGRect(x: 0, y: 0, width: 7, height: 12))
+        XCTAssertEqual(container.subviews.first?.subviews.first?.subviews.first?.frame, CGRect(x: 1, y: 1, width: 5, height: 10))
+        XCTAssertEqual(container.subviews.last?.frame, CGRect(x: 1, y: 12, width: 5, height: 20))
+    }
+
     func testAnimation() {
         let forceViewConfig: (View) -> Void = { _ in }
         var redSquare: View? = nil
diff --git a/LayoutKitTests/ViewRecyclerViewStorageTests.swift b/LayoutKitTests/ViewRecyclerViewStorageTests.swift
index 133bbb91..a8efebc6 100644
--- a/LayoutKitTests/ViewRecyclerViewStorageTests.swift
+++ b/LayoutKitTests/ViewRecyclerViewStorageTests.swift
@@ -40,8 +40,8 @@ class ViewRecyclerViewStorageTests: XCTestCase {
         storage.add(view: view1)
         storage.add(view: view2)
 
-        XCTAssertEqual(storage.popView(withReuseGroup: "group1"), view1)
         XCTAssertEqual(storage.popView(withReuseGroup: "group1"), view2)
+        XCTAssertEqual(storage.popView(withReuseGroup: "group1"), view1)
         XCTAssertNil(storage.popView(withReuseGroup: "group1"))
     }
 
@@ -52,8 +52,8 @@ class ViewRecyclerViewStorageTests: XCTestCase {
         storage.add(view: view1)
         storage.add(view: view2)
 
-        XCTAssertEqual(storage.popView(withReuseGroup: "group1"), view1)
-        XCTAssertNil(storage.popView(withReuseId: "1"), "View should already been popped")
+        XCTAssertEqual(storage.popView(withReuseGroup: "group1"), view2)
+        XCTAssertNil(storage.popView(withReuseId: "2"), "View should already been popped")
     }
 
     func testRemoveView() {
diff --git a/Sources/ViewRecycler.swift b/Sources/ViewRecycler.swift
index f35d50b9..a632e4d6 100644
--- a/Sources/ViewRecycler.swift
+++ b/Sources/ViewRecycler.swift
@@ -34,13 +34,9 @@ final class ViewRecycler {
 
         // If we have a recyclable view that matches type and id, then reuse it.
         if let viewReuseId = viewReuseId, let view = self.viewStorage.popView(withReuseId: viewReuseId) {
-            // Remove from superview to avoid view cycles
-            view.removeFromSuperview()
             return view
         }
         if let viewGroup = viewReuseGroup, let view = self.viewStorage.popView(withReuseGroup: viewGroup) {
-            // Remove from superview to avoid view cycles
-            view.removeFromSuperview()
             return view
         }
 
diff --git a/Sources/ViewRecyclerViewStorage.swift b/Sources/ViewRecyclerViewStorage.swift
index 8f00cd7f..8d61c797 100644
--- a/Sources/ViewRecyclerViewStorage.swift
+++ b/Sources/ViewRecyclerViewStorage.swift
@@ -10,10 +10,10 @@ import Foundation
 
 final class ViewRecyclerViewStorage {
 
-    private var views: Set<View> = []
+    private var views: [View] = []
 
     func add(view: View) {
-        self.views.insert(view)
+        self.views.insert(view, at: 0)
     }
 
     func popView(withReuseId viewId: String) -> View? {
@@ -24,6 +24,7 @@ final class ViewRecyclerViewStorage {
     }
 
     func popView(withReuseGroup viewGroup: String) -> View? {
+
         guard let index = self.views.index(where: { $0.viewReuseGroup == viewGroup }) else {
             return nil
         }

From 8ac7178aa1c043abb9e3e57d4a7b8c6c409e8c31 Mon Sep 17 00:00:00 2001
From: Andre Stenvall <andre@stenvall.me>
Date: Tue, 12 Dec 2017 15:20:22 +0100
Subject: [PATCH 10/12] Use EdgeInsets instead of UIEdgeInsets

---
 LayoutKitTests/LayoutArrangementTests.swift | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/LayoutKitTests/LayoutArrangementTests.swift b/LayoutKitTests/LayoutArrangementTests.swift
index 184534ba..8fd0177d 100644
--- a/LayoutKitTests/LayoutArrangementTests.swift
+++ b/LayoutKitTests/LayoutArrangementTests.swift
@@ -62,7 +62,7 @@ class LayoutArrangementTests: XCTestCase {
             viewReuseGroup: "colorView",
             sublayouts: [
                 InsetLayout(
-                    insets: UIEdgeInsets(top: 1, left: 1, bottom: 1, right: 1),
+                    insets: EdgeInsets(top: 1, left: 1, bottom: 1, right: 1),
                     viewReuseGroup: "dummy",
                     sublayout: SizeLayout(width: 5, height: 10, viewReuseGroup: "colorView", config: forceViewConfig),
                     config: forceViewConfig

From 379f6ace54430e4f4130f06ad84e219ee518a524 Mon Sep 17 00:00:00 2001
From: Andre Stenvall <andre@stenvall.me>
Date: Thu, 14 Dec 2017 14:21:27 +0100
Subject: [PATCH 11/12] Add viewReuseGroup to ButtonLayout

---
 Sources/Layouts/ButtonLayout.swift | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Sources/Layouts/ButtonLayout.swift b/Sources/Layouts/ButtonLayout.swift
index ef5e5b95..2d743883 100644
--- a/Sources/Layouts/ButtonLayout.swift
+++ b/Sources/Layouts/ButtonLayout.swift
@@ -36,6 +36,7 @@ open class ButtonLayout<Button: UIButton>: BaseLayout<Button>, ConfigurableLayou
                 alignment: Alignment = ButtonLayoutDefaults.defaultAlignment,
                 flexibility: Flexibility = ButtonLayoutDefaults.defaultFlexibility,
                 viewReuseId: String? = nil,
+                viewReuseGroup: String? = nil,
                 config: ((Button) -> Void)? = nil) {
 
         self.type = type
@@ -43,7 +44,7 @@ open class ButtonLayout<Button: UIButton>: BaseLayout<Button>, ConfigurableLayou
         self.image = image
         self.font = font
         self.contentEdgeInsets = contentEdgeInsets ?? ButtonLayout.defaultContentEdgeInsets(for: type, image: image)
-        super.init(alignment: alignment, flexibility: flexibility, viewReuseId: viewReuseId, config: config)
+        super.init(alignment: alignment, flexibility: flexibility, viewReuseId: viewReuseId, viewReuseGroup: viewReuseGroup, config: config)
     }
 
     private static func defaultContentEdgeInsets(for type: ButtonLayoutType, image: ButtonLayoutImage) -> UIEdgeInsets {

From 7030f74ea990e9df61f79f49c49022ed15013972 Mon Sep 17 00:00:00 2001
From: Andre Stenvall <andre@stenvall.me>
Date: Mon, 18 Dec 2017 09:09:10 +0100
Subject: [PATCH 12/12] Fix view reference cycle

---
 LayoutKitTests/LayoutArrangementTests.swift | 53 ++++++++++++---------
 Sources/LayoutArrangement.swift             | 17 +++++++
 2 files changed, 47 insertions(+), 23 deletions(-)

diff --git a/LayoutKitTests/LayoutArrangementTests.swift b/LayoutKitTests/LayoutArrangementTests.swift
index 8fd0177d..24944aed 100644
--- a/LayoutKitTests/LayoutArrangementTests.swift
+++ b/LayoutKitTests/LayoutArrangementTests.swift
@@ -53,41 +53,48 @@ class LayoutArrangementTests: XCTestCase {
         XCTAssertEqual(container.subviews[2].frame, CGRect(x: 0, y: 30, width: 5, height: 30))
     }
 
-    func testSubViewsSameViewReuseGroup() {
+    func testViewReuseCircularReferenceDisconnection() {
 
         let forceViewConfig: (View) -> Void = { _ in }
 
-        let leftSubTree = StackLayout(
-            axis: .horizontal,
-            viewReuseGroup: "colorView",
+        let layoutsForReusedView = StackLayout(
+            axis: .vertical,
+            viewReuseGroup: "A",
             sublayouts: [
-                InsetLayout(
-                    insets: EdgeInsets(top: 1, left: 1, bottom: 1, right: 1),
-                    viewReuseGroup: "dummy",
-                    sublayout: SizeLayout(width: 5, height: 10, viewReuseGroup: "colorView", config: forceViewConfig),
+                SizeLayout(
+                    size: .zero,
+                    viewReuseGroup: "B",
                     config: forceViewConfig
                 )
             ],
             config: forceViewConfig
         )
 
-        let right = SizeLayout(width: 5, height: 20, viewReuseGroup: "dummy", config: forceViewConfig)
-        let stack = StackLayout(axis: .vertical, sublayouts: [leftSubTree, right])
-        let container = View()
+        let newLayouts = StackLayout(
+            axis: .vertical,
+            viewReuseGroup: "B",
+            sublayouts: [
+                SizeLayout(
+                    size: .zero,
+                    viewReuseGroup: "A",
+                    sublayout: SizeLayout(
+                        size: .zero,
+                        viewReuseGroup: "A",
+                        config: forceViewConfig
+                    ),
+                    config: forceViewConfig
+                )
+            ],
+            config: forceViewConfig
+        )
 
-        // Make sure that we reuse the views in correct order, otherwise we get a view cycle
-        // that will cause a crash.
-        stack.arrangement().makeViews(in: container)
-        XCTAssertEqual(container.subviews.first?.frame, CGRect(x: 0, y: 0, width: 7, height: 12))
-        XCTAssertEqual(container.subviews.first?.subviews.first?.frame, CGRect(x: 0, y: 0, width: 7, height: 12))
-        XCTAssertEqual(container.subviews.first?.subviews.first?.subviews.first?.frame, CGRect(x: 1, y: 1, width: 5, height: 10))
-        XCTAssertEqual(container.subviews.last?.frame, CGRect(x: 1, y: 12, width: 5, height: 20))
+        let container = View()
+        layoutsForReusedView.arrangement().makeViews(in: container)
+        newLayouts.arrangement().makeViews(in: container)
 
-        stack.arrangement().makeViews(in: container)
-        XCTAssertEqual(container.subviews.first?.frame, CGRect(x: 0, y: 0, width: 7, height: 12))
-        XCTAssertEqual(container.subviews.first?.subviews.first?.frame, CGRect(x: 0, y: 0, width: 7, height: 12))
-        XCTAssertEqual(container.subviews.first?.subviews.first?.subviews.first?.frame, CGRect(x: 1, y: 1, width: 5, height: 10))
-        XCTAssertEqual(container.subviews.last?.frame, CGRect(x: 1, y: 12, width: 5, height: 20))
+        XCTAssertEqual(container.subviews.count, 1)
+        XCTAssertEqual(container.subviews.first?.subviews.count, 1)
+        XCTAssertEqual(container.subviews.first?.subviews.first?.subviews.count, 1)
     }
 
     func testAnimation() {
diff --git a/Sources/LayoutArrangement.swift b/Sources/LayoutArrangement.swift
index 2bcacfde..b06ae14e 100644
--- a/Sources/LayoutArrangement.swift
+++ b/Sources/LayoutArrangement.swift
@@ -163,6 +163,12 @@ extension View {
      will be adjusted so that its absolute position on the screen does not change.
      */
     fileprivate func addSubview(_ view: View, maintainCoordinates: Bool) {
+
+        // Disconnect reference cycle
+        if isChildOf(view) {    
+            removeFromSuperview()
+        }
+
         if maintainCoordinates {
             let frame = view.convertToAbsoluteCoordinates(view.frame)
             addSubview(view)
@@ -171,5 +177,16 @@ extension View {
             addSubview(view)
         }
     }
+
+    fileprivate func isChildOf(_ view: View) -> Bool {
+
+        guard let superview = self.superview else { return false }
+
+        if superview == view {
+            return true
+        }
+
+        return superview.isChildOf(view)
+    }
 }