Swift 如何强制创建新的UIViewControllerRenatable｜更新Make UIViewController上的视图

虽然不是makeUIViewController，但updateUIViewController是.您可以更改UIHostingController中显示的视图.

func makeUIViewController(context: Context) -> UIHostingController<ContentM> {
    print("makeUI")
    return UIHostingController(rootView: rootView)
}
func updateUIViewController(_ uiViewController: UIHostingController<ContentM>, context: Context) {
    uiViewController.rootView = rootView
    print("updateUI")
}

请注意，当您在两个视图之间切换时，这将中断您想要执行的任何动画.SwiftUI无法设置uiViewController.rootView = rootView的动画.

或者，您可以在每次发生切换时更改MyView‘S ID:

MyView(rootView: rootView()).id(isGreen)

这将在您每次更改视图时重新创建一个新的UIHostingController，并可以设置更改的动画.然而，这只是为两个MyView之间的变化设置动画，恰好看起来与在OrangeView和GreenView之间变化的动画相似(两者都是交叉淡入淡出).如果您有其他动画，如设置某物比例的动画:

Text("Foo").scaleEffect(isGreen ? 1 : 2)

则动画仍将是交叉淡入淡出，而不是zoom 动画.

我发现的第三种方法是用一个@Observable的包装纸把Bool包起来，然后把它放在Environment里.

@Observable
class BoolWrapper: ExpressibleByBooleanLiteral {
    var bool: Bool
    required init(booleanLiteral value: Bool) {
        bool = value
    }
}

private struct ControllerView<Content: View>: View {
    struct MyView<ContentM: View>: UIViewControllerRepresentable {
        let rootView: () -> ContentM
        
        init(@ViewBuilder rootView: @escaping () -> ContentM) {
            self.rootView = rootView
            print("init MyView")
        }
        
        func makeUIViewController(context: Context) -> UIHostingController<ContentM> {
            print("makeUI")
            return UIHostingController(rootView: rootView())
        }
        func updateUIViewController(_ uiViewController: UIHostingController<ContentM>, context: Context) {
            print("updateUI")
        }
    }
    
    
    let rootView: () -> Content
    let isGreen: BoolWrapper
    
    init(isGreen: BoolWrapper,@ViewBuilder rootView: @escaping () -> Content) {
        self.rootView = rootView
        self.isGreen = isGreen
    }
    
    var body: some View {
        ZStack {
            MyView(rootView: rootView)
            
            Button {
                withAnimation {
                    isGreen.bool.toggle()
                }
            } label: {
                Text("Change")
            }
        }
    }
}

struct ContentView: View {
    @State var isGreen: BoolWrapper = true
    
    var body: some View {
        ControllerView(isGreen: isGreen) {
            GreenOrangeWrapper().environment(isGreen)
        }
    }
}

struct GreenOrangeWrapper: View {
    @Environment(BoolWrapper.self) var boolWrapper
    
    var body: some View {
        if boolWrapper.bool {
            GreenView()
        } else {
            OrangeView()
        }
    }
}

现在动画都被保存下来了.