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Can you animate a SwiftUI View on disappear?(你能在消失时为SwiftUI视图设置动画吗？)

转载 作者：bug小助手 更新时间：2023-10-25 15:47:12 25 4
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I have a SwiftUI View which has a custom animation that runs onAppear. I am trying to get the view to animate onDisappear too but it just immediately vanishes.

我有一个SwiftUI视图，它有一个在外观上运行的自定义动画。我也试着让它的视点变成动画，但它马上就消失了。


The below example reproduces the problem - the MyText view should slide in from the left and slide out to the right. The id modifier is used to ensure a new view is rendered each time the value changes, and I have confirmed that both onAppear and onDisappear are indeed called each time, but the animation onDisappear never visibly runs. How can I achieve this?

下面的示例再现了这个问题-MyText视图应该从左侧滑入，然后滑出到右侧。Id修饰符用于确保每次值更改时都会呈现一个新的视图，并且我已经确认，每次确实都会调用onOuar和onDis现，但动画onDisshow从不会明显地运行。我怎样才能做到这一点呢？


struct Survey: View {
  @State private var id = 0

  var body: some View {
    VStack {
      MyText(text: "\(id)").id(id)

      Button("Increment") {
        self.id += 1
      }
    }
  }

  struct MyText: View {
    @State private var offset: CGFloat = -100
    let text: String

    var body: some View {
      return Text(text)
        .offset(x: offset)
        .onAppear() {
          withAnimation(.easeInOut(duration: 2)) {
            self.offset = 0
          }
        }
        .onDisappear() {
          withAnimation(.easeInOut(duration: 2)) {
            self.offset = 100
          }
        }
    }
  }
}

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优秀答案推荐

Probably you wanted transition, something like

可能你想要过渡，就像


demo


Update: re-tested with Xcode 13.4 / iOS 15.5

更新：使用Xcode 13.4/iOS 15.5重新测试


struct Survey: View {
    @State private var id = 0

    var body: some View {
        VStack {
            MyText(text: "\(id)")

            Button("Increment") {
                self.id += 1
            }
        }
    }

    struct MyText: View {
        var text: String


        var body: some View {
            Text("\(text)").id(text)
                .frame(maxWidth: .infinity)
                .transition(.slide)
                .animation(.easeInOut(duration: 2), value: text)
        }
    }
}


I'm afraid it can't work since the .onDisappear modifier is called once the view is hidden.
However there is a nice answer here :
Is there a SwiftUI equivalent for viewWillDisappear(_:) or detect when a view is about to be removed?

我担心它不能工作，因为一旦隐藏了视图，就会调用.onDis现修饰符。然而，这里有一个很好的答案：是否有一个SwiftUI等同于viewWillDis现(_：)或检测何时要删除一个视图？



maybe sth. like that

也许是某样东西。就像这样


func disappearAnimation() {
    withAnimation(.easeInOut(duration: animationDuration)) {
        // animation
    }
                  
    DispatchQueue.main.asyncAfter(deadline: .now() + animationDuration) {
        dismiss()
    }
    
}

更多回答

Well done! :) However, about the question, strictly, that's too bad this is still not available natively in SwiftUI in 2021.

做得好！：)然而，关于这个问题，严格来说，这太糟糕了，2021年SwiftUI仍然不能本地提供。

Also as a follow up question... what is the benefit of using a binding in the sub-view? It appears to work either way.

还有一个后续问题..。在子视图中使用绑定有什么好处？无论是哪种方式，它似乎都能奏效。

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