iOS 16 Beta AnimationView in UIViewRepresentable won't play

[aharriscrowne]

Which Version of Lottie are you using?

Lottie 3.4

Expected Behavior

Calling animationView.play(completion:) should play the animation

Actual Behavior

Calling animationView.play(completion:) dies. When rendering is .mainThread, it checks for window, but didMoveToWindow is never called. Not clear if this is iOS 16 intended behavior or a beta bug.

Animation JSON

[calda]

I'm not familiar with the SwiftUI guarantees around UIViewRepresentable and UIWindows. I believe other folks have successfully used the Main Thread rendering engine with SwiftUI and I haven't heard of this issue yet, so I wonder if this is an iOS 16 specific issue.

[calda]

Does it work on iOS 15 but specifically not on iOS 16?

[aharriscrowne]

It is specifically iOS 16. I just did a test project and discovered that it is even more specific. The problem occurs when my UIViewRepresentable (called LottieView) which makes the AnimationView is nested in a SwiftUI Button label. Like this:

var body: some View {
        VStack(spacing: 15) {
            Button {
                selected = true
            } label: {
                if selected {
                    LottieView()
                } else {
                    Text("Push me")
                }
            }

            Text("Hello, world!")
        }
    }

This is not specific to a Lottie usage; any UIView you use will not call didMoveToWindow(). I am filing a Apple bug report on it; seems like it is probably not intended behavior.

[calda]

Thanks for filing a bug with Apple -- agree that this sounds like a iOS 16 SwiftUI regression

[ryngonzalez]

@aharriscrowne Is there a link to the radar submission to follow along?

[aharriscrowne]

This now functions correctly in iOS 16.1. It might also work in 16.0--I have tested in the 16.0 simulator and it works there.