Can you animate a SwiftUI View on disappear?

Question

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.

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?

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
          }
        }
    }
  }
}

score 3 · Accepted Answer · edited Aug 23 '22 at 15:15

3

Probably you wanted transition, something like

Update: re-tested with Xcode 13.4 / iOS 15.5

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)
        }
    }
}

edited Aug 23 '22 at 15:15

Martijn Pieters

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answered Jan 21 '21 at 16:57

Asperi

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Well done! :) However, about the question, strictly, that's too bad this is still not available natively in SwiftUI in 2021. – Moose Jan 21 '21 at 18:57
Also as a follow up question... what is the benefit of using a binding in the sub-view? It appears to work either way. – James Allardice Jan 23 '21 at 11:21

score 1 · Answer 2 · answered Jan 21 '21 at 18:52

1

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?

answered Jan 21 '21 at 18:52

Moose

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Can you animate a SwiftUI View on disappear?

2 Answers2