SwiftUI Animation Bug inside Scroll View

Question

I am relatively new to SwiftUI and I am trying to implement animated loader to my app. It works fine until I scroll my content inside scroll view down and then move back to trigger pull to refresh. Circles started to jump though they should only increase and decrease their size one by one.

My code is

struct ActivityIndicator: View {

    var isShowing: Bool
    @State private var shouldAnimate = false

    init(isShowing: Bool) {
        self.isShowing = isShowing
    }

    var body: some View {
        HStack(alignment: .center) {
            Circle()
                .fill(Color.mainAccent)
                .frame(width: 20, height: 20)
                .scaleEffect(shouldAnimate ? 1.0 : 0.5)
                .animation(Animation.easeInOut(duration: 0.5).repeatForever())
            Circle()
                .fill(Color.mainAccent)
                .frame(width: 20, height: 20)
                .scaleEffect(shouldAnimate ? 1.0 : 0.5)
                .animation(Animation.easeInOut(duration: 0.5).repeatForever().delay(0.3))
            Circle()
                .fill(Color.mainAccent)
                .frame(width: 20, height: 20)
                .scaleEffect(shouldAnimate ? 1.0 : 0.5)
                .animation(Animation.easeInOut(duration: 0.5).repeatForever().delay(0.6))
        }
            .opacity(self.isShowing ? 1 : 0)
            .onAppear {
                self.shouldAnimate = true
            }
    }
}

I have read few articles related to my case and it seems that I might had to use withAnimation (Explicit) instead .animation (Implicit) but I can't make it work properly.

Btw I connect my Activity Indicator to the scrollView using Loading View modifier and it looks like this

struct LoadingView: ViewModifier {
    @Binding var isShowing: Bool

    func body(content: Content) -> some View {
            ZStack(alignment: .center) {
                content
                    .disabled(self.isShowing)
                    .blur(radius: self.isShowing ? 3 : 0)

                ActivityIndicator(isShowing: isShowing)
            }
    }
}

Any ideas and suggestions are appreciated I am really stuck. Thanks

Asperi · Accepted Answer · 2021-05-14 11:24:17Z

3

Try to link all your animations to related state, like

var body: some View {
    HStack(alignment: .center) {
        Circle()
            .fill(Color.mainAccent)
            .frame(width: 20, height: 20)
            .scaleEffect(shouldAnimate ? 1.0 : 0.5)
            .animation(Animation.easeInOut(duration: 0.5).repeatForever(), 
                       value: shouldAnimate)   // << here !!

answered May 14, 2021 at 11:24

Asperi

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NilsBerni · Accepted Answer · 2021-05-23 09:11:38Z

0

If you have any problems with the previous answer, try removing the .animation and replace it with withAnimation:

https://developer.apple.com/documentation/swiftui/withanimation(_:_:)

The advantage of that is that it does not affect other animations.

answered May 23, 2021 at 9:11

NilsBerni

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