Stop swiftUI animation and skip to destination value - swiftui

Question

I am animating the remaining time for some scenes in my app. I have the issue that when the user interrupts this scene by going to the next scene, the animation doesn't stop
This code is a simplified version of what is happening:
struct ContentView: View {
#State private var remaining: Int = 40
#State private var sceneIndex: Int = 0
var body: some View {
VStack(spacing: 30) {
Text("Remaining:")
EmptyView().modifier(DoubleModifier(value: remaining))
Button(action: {
self.sceneIndex += 1
if self.sceneIndex == 1 {
withAnimation(.linear(duration: 10)) {
self.remaining = 30
}
} else {
withAnimation(.linear(duration: 0)) {
self.remaining = 30 // changing this to any other value will stop the animation
}
}
}) {
Text("Go to next scene")
}
}
}
}
struct DoubleModifier: AnimatableModifier {
private var value: Double
init(value: Int) {
self.value = Double(value)
}
var animatableData: Double {
get { value }
set { value = newValue }
}
func body(content: Content) -> some View {
Text("\(Int(value)) seconds remaining")
}
}
What is happening is that when the user clicks the countdown animation is initialised with a duration of 10 seconds and will set the remaining time from 40 to 30 seconds. Now when the user clicks the skip button, the animation should stop and go to the 30 seconds remaining. However, it still shows the animation from 40 to 30 (somewhere in between).
If I change the self.remaining to 30 in the else statement, the value is not updated since it is already set to 30, but internally it is still animating.
If I change the self.remaining to any other valid value than 30, for example self.remaining = 29 the animation is indeed immediately stopped.
I could replace the content in the else statement by:
withAnimation(.linear(duration: 0)) {
self.remaining = 29
DispatchQueue.main.async {
self.remaining = 30
}
}
Which does work but feels very messy and in my case it is not always possible to use DispatchQueue.main.async
Is there another, better, way to stop the animation and skip to the destination value?
Is it maybe somehow possible to assign some sort of identifier to the self.remaining = 30 in the else statement such that swiftUI knows the value actually did change even though it factually didn't so that swiftUI stops the animation?

Answer 1

It is not clear what's the logic planned by step from scene-to-scene, but goal as it is postulated now in question can be achieved with the following body:
var body: some View {
VStack(spacing: 30) {
Text("Remaining:")
EmptyView().modifier(DoubleModifier(value: remaining)).id(sceneIndex)
Button(action: {
self.sceneIndex += 1
withAnimation(.linear(duration: 10)) {
self.remaining = 30
}
}) {
Text("Go to next scene")
}
}
}