fix editing TextField causes re-render

CMakeLists.txt

@@ -6,7 +6,7 @@ set(CMAKE_CONFIGURATION_TYPES Debug Release CACHE STRING INTERNAL FORCE)
 set(CMAKE_TOOLCHAIN_FILE "${CMAKE_CURRENT_LIST_DIR}/cmake/ios.cmake")
 
 project(fcitx5-ios VERSION 0.1.0 LANGUAGES CXX Swift)
-set(CMAKE_OSX_DEPLOYMENT_TARGET 15)
+set(CMAKE_OSX_DEPLOYMENT_TARGET 17) # I really need onChange for focus out.
 set(CMAKE_Swift_LANGUAGE_VERSION 5.9)
 set(CMAKE_CXX_STANDARD 17)
 

src/config/StringView.swift

@@ -4,26 +4,28 @@ struct StringView: View, OptionViewProtocol {
   let label: String
   let data: [String: Any]
   @Binding var value: Any
+  @State private var text: String = ""
+  @FocusState private var isFocused: Bool
 
   var body: some View {
     HStack {
       if !label.isEmpty {
         Text(label)
       }
-      TextField(
-        "",
-        text: Binding<String>(
-          get: { value as! String },
-          set: {
-            // Avoid unnecessary write.
-            if value as! String != $0 {
-              value = $0
-            }
+      TextField("", text: $text)
+        .focused($isFocused)
+        // Don't update real-time. It changes parent state so the whole view is re-rendered.
+        // Don't use onSubmit. It requires Enter key to be pressed.
+        .onChange(of: isFocused) {
+          // Avoid unnecessary write.
+          if !isFocused && value as! String != text {
+            value = text
           }
-        )
-      )
-      // Leading for List item, trailing for String option.
-      .multilineTextAlignment(label.isEmpty ? .leading : .trailing)
+        }
+        // Leading for List item, trailing for String option.
+        .multilineTextAlignment(label.isEmpty ? .leading : .trailing)
+    }.onAppear {
+      text = value as! String
     }
   }
 }