SwiftUI中的动态跃迁

Question

我希望能够根据状态转换使用不同的转换。例如，如果我从.one => .three出发，我想在删除时淡出ViewOne。如果我从.one => .two出发，我想在移除时将ViewOne移到左边。现在，我有这样的东西(显然，它只适用于.one => .two的转换)：

ZStack {
    if state == .one {
        ViewOne()
            .transition(.asymmetric(insertion: .move(edge: .trailing), removal: .move(edge: .leading)))
    }

    if state == .two {
        ViewTwo()
            .transition(.asymmetric(insertion: .move(edge: .trailing), removal: .move(edge: .leading)))
    }

    if state == .three {
        ViewThree()
            .transition(.asymmetric(insertion: .opacity, removal: .identity))
    }
}

如何根据状态动态地更改转换？

更新：这里有一个更完整的示例：

enum Screen {
    case susi, onboarding, home
}

struct ContentView: View {
    @State var screen: Screen = .susi
    @State var transition: AnyTransition = .asymmetric(insertion: .identity, removal: .move(edge: .leading))
    
    var body: some View {
        ZStack {
            if screen == .susi {
                ViewOne()
                    .transition(transition)

            }
            if screen == .onboarding {
                ViewTwo()
                    .transition(.asymmetric(insertion: .move(edge: .trailing), removal: .move(edge: .leading)))
            }
            if screen == .home {
                ViewThree()
                    .transition(.asymmetric(insertion: .opacity, removal: .identity))
            }
        }
        .onAppear {
            DispatchQueue.main.asyncAfter(deadline: .now() + 5) {
                withAnimation(.default) {
                    self.transition = .asymmetric(insertion: .identity, removal: .opacity)
                    self.screen = .home
                }
            }
        }
    }
}

Answer 1

对于那些用同样的问题阅读这篇文章的人，一种解决方案是切换视图的id属性。一些搜索，所以引导我使用这种技术，这显然是重置动画为一个视图。

import SwiftUI

enum Screen {
    case susi, onboarding, home
}

struct ContentView: View {
    @State var screen: Screen = .susi
    @State var transition: AnyTransition = .move(edge: .leading)
    @State var viewId = UUID().uuidString
    
    var body: some View {
        ZStack {
            if screen == .susi {
                ViewOne()
                    .transition(transition)

            }
            if screen == .onboarding {
                ViewTwo()
                    .transition(.asymmetric(insertion: .move(edge: .trailing), removal: .move(edge: .trailing)))
            }
            if screen == .home {
                ViewThree()
                    .transition(.asymmetric(insertion: .opacity, removal: .move(edge: .bottom)))
            }
        }
        .id(viewId)
        .onAppear {
            DispatchQueue.main.asyncAfter(deadline: .now() + 5) {
                withAnimation(.default) {
                    self.screen = .onboarding
                }
                
                DispatchQueue.main.asyncAfter(deadline: .now() + 5) {
                    withAnimation(.default) {
                        self.screen = .susi
                    }
                    
                    DispatchQueue.main.asyncAfter(deadline: .now() + 5) {
                        self.transition = .opacity
                        self.viewId = UUID().uuidString
                        
                        withAnimation(.default) {
                            self.screen = .home
                        }
                        
                        DispatchQueue.main.asyncAfter(deadline: .now() + 5) {
                            self.transition = .move(edge: .top)
                            self.viewId = UUID().uuidString
                            
                            withAnimation(.default) {
                                self.screen = .susi
                            }
                            
                            DispatchQueue.main.asyncAfter(deadline: .now() + 5) {
                                self.transition = .move(edge: .leading)
                                self.viewId = UUID().uuidString
                                
                                withAnimation(.default) {
                                    self.screen = .onboarding
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}

最后，我修改了id of ViewOne，而不是整个ZStack，因为我担心这样做会产生一些意想不到的SwiftUI怪癖。同样的技术，只是把它应用到不同的视图中。