scopedanimationoffsetbug's Introduction

SwiftUI Scoped Offset Animation Not Working

This repository demonstrates a SwiftUI bug when the .offset() modifier doesn't work when used inside a scoped animation (.animation(_:body:)).

The target view has .opacity() and .offset() modifiers in a scoped animation (iOS 17):

Text("Hello, world!")
    .animation(.default) {
        $0
            .opacity(animate ? 1 : 0.2)
            .offset(y: animate ? 0 : 100) // <-- DOESN'T WORK
    }

But only the .opacity() works when the state is changed directly or withAnimation{}. The .offset() only works when using withAnimation{}, even though it should animate in both cases, like opacity.

The code to replicate this:

import SwiftUI

struct ContentView: View {
    
    @State private var animate = false
    
    var body: some View {
        VStack(spacing: 20) {
            Button("Toggle Scoped Animation") {
                animate.toggle()
            }
            Button("Toggle withAnimation{}") {
                withAnimation {
                    animate.toggle()
                }
            }
            Text("Hello, world!")
                .animation(.default) {
                    $0
                        .opacity(animate ? 1 : 0.2)
                        .offset(y: animate ? 0 : 100) // <-- DOESN'T WORK
                }
        }
    }
}

#Preview {
    ContentView()
}

@main
struct ScopedAnimationOffsetBugApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
        }
    }
}