SwiftUI：如何在一段时间后删除视图

Question

I have this animation code:

struct CheckmarkAnimation: View {
    @State private var isAnimating = false

    var body: some View {
        ZStack {
            Circle()
                .trim(to: isAnimating ? 1:0)
                .stroke(.green, lineWidth: 3)
                .frame(width: 100, height: 100)
                .animation(.easeInOut(duration: 1), value: isAnimating)
            
            Image(systemName: "checkmark")
                .foregroundColor(.green)
                .font(.largeTitle)
                .scaleEffect(isAnimating ? 1.5 : 0)
                .animation(.spring(response: 0.5, dampingFraction: 0.4).delay(1), value: isAnimating)
        }
        .onAppear {
            isAnimating.toggle()
        }
    }
}

I would like this view to disappear after the scaling effect on the checkmark ends. How do I do this?

Answer 1

Here are 2 ways to do it:

Change drawing color to .clear after 2 seconds

Here's a way to have it disappear (turn invisible but still take up space). Change the drawing color to .clear after 2 seconds:

struct CheckmarkAnimation: View {
    @State private var isAnimating = false
    @State private var color = Color.green
    
    var body: some View {
        ZStack {
            Circle()
                .trim(to: isAnimating ? 1:0)
                .stroke(color, lineWidth: 3)
                .frame(width: 100, height: 100)
                .animation(.easeInOut(duration: 1), value: isAnimating)
            
            Image(systemName: "checkmark")
                .foregroundColor(color)
                .font(.largeTitle)
                .scaleEffect(isAnimating ? 1.5 : 0.001)
                .animation(.spring(response: 0.5, dampingFraction: 0.4).delay(1), value: isAnimating)
                
        }
        .onAppear {
            isAnimating.toggle()
            withAnimation(.linear(duration: 0.01).delay(2)) {
                color = .clear
            }
        }
    }
}

---

Use .scaleEffect() on ZStack

Insert this scale animation before the .onAppear :

.scaleEffect(isAnimating ? 0.001 : 1)
.animation(.linear(duration: 0.01).delay(2), value: isAnimating)
.onAppear {
    isAnimating.toggle()
}

Note : Use 0.001 instead of 0 in scaleEffect to avoid

ignoring singular matrix: ProjectionTransform

messages in the console.

Answer 2

.scaleEffect() on ZStack is an elegant solution.

struct CheckmarkAnimation: View {
    @State private var isAnimating = false
    @State private var color = Color.green
    
    var body: some View {
        ZStack {
            Circle()
                .trim(to: isAnimating ? 1:0)
                .stroke(color, lineWidth: 3)
                .frame(width: 100, height: 100)
                .animation(.easeInOut(duration: 1), value: isAnimating)
            
            Image(systemName: "checkmark")
                .foregroundColor(color)
                .font(.largeTitle)
                .scaleEffect(isAnimating ? 1.5 : 0)
                .animation(.spring(response: 0.5, dampingFraction: 0.4).delay(1), value: isAnimating)
                
        }
        .scaleEffect(isAnimating ? 0 : 1)
        .animation(.linear(duration: 0.01).delay(2), value: isAnimating)
        .onAppear {
            isAnimating.toggle()
        }
    }
}

This code works and makes the view disappear^^