Add dynamic color shorthand.

README.md

@@ -4,7 +4,7 @@
 [![Build Status](https://github.com/lipka/Color/workflows/Tests/badge.svg)](https://github.com/lipka/Color/actions)
 ![Swift Version](https://img.shields.io/badge/swift-5.2.0-orange.svg)
 
-Simple extensions for working with `Color` (Swift UI) and `UIColor` (UIKit).
+Simple extensions for working with `Color` (SwiftUI) and `UIColor` (UIKit).
 
 ## Installation
 
@@ -49,4 +49,14 @@ import Button
 let button = Button()
 button.setBackgroundColor(.blue, for: .normal)
 button.setBackgroundColor(.blue.adjust(0.1), for: .highlighted)
-```
+```
+
+### Dynamic Colors
+
+Shorthand notation for creating dynamic colors (light/dark mode).
+
+```swift
+Color(light: Color.white, dark: Color.black)
+
+UIColor(light: UIColor.white, dark: UIColor.black)
+```

Sources/Color/Color+Dynamic.swift

@@ -0,0 +1,14 @@
+import SwiftUI
+
+@available(iOS 14.0, *)
+extension Color {
+    init(
+        light lightColor: @escaping @autoclosure () -> Color,
+        dark darkColor: @escaping @autoclosure () -> Color
+    ) {
+        self.init(UIColor(
+            light: UIColor(lightColor()),
+            dark: UIColor(darkColor())
+        ))
+    }
+}

Sources/Color/UIColor+Dynamic.swift

@@ -0,0 +1,22 @@
+import UIKit
+
+@available(iOS 13.0, *)
+extension UIColor {
+    convenience init(
+        light lightColor: @escaping @autoclosure () -> UIColor,
+        dark darkColor: @escaping @autoclosure () -> UIColor
+    ) {
+        self.init { traitCollection in
+            switch traitCollection.userInterfaceStyle {
+            case .light:
+                return lightColor()
+            case .dark:
+                return darkColor()
+            case .unspecified:
+                return lightColor()
+            @unknown default:
+                return lightColor()
+            }
+        }
+    }
+}

Tests/ColorTests/DynamicColorTests.swift

@@ -0,0 +1,28 @@
+import XCTest
+import SwiftUI
+import UIKit
+@testable import Color
+
+final class DynamicTests: XCTestCase {
+    @available(iOS 14.0, *)
+    func testDynamicColor() {
+        let c = Color(light: Color.black, dark: Color.white)
+        let rc = UIColor(c).resolvedColor(with: UITraitCollection(userInterfaceStyle: .dark))
+
+        var r: CGFloat = 0, g: CGFloat = 0, b: CGFloat = 0, o: CGFloat = 0
+        rc.getRed(&r, green: &g, blue: &b, alpha: &o)
+
+        XCTAssertEqual(r, 0)
+        XCTAssertEqual(g, 0)
+        XCTAssertEqual(b, 0)
+        XCTAssertEqual(o, 1)
+    }
+
+    @available(iOS 13.0, *)
+    func testDynamicUIColor() {
+        let c = UIColor(light: UIColor.black, dark: UIColor.white)
+        let rc = c.resolvedColor(with: UITraitCollection(userInterfaceStyle: .dark))
+
+        XCTAssertEqual(rc, UIColor.white)
+    }
+}