swiftui - SwiftUI 按钮的 Aura 动画

Question

如何制作下面的动画？触摸按钮时会出现灵气，整个盒子就像手指的重量一样收缩。

struct ContentView: View {
    
    var body: some View {
        Button(action: {
            
        }, label: {
                Image(systemName: "camera")
                        .font(.title)
                        .opacity(1)
        })
        .padding(.horizontal, 20)
        .frame(height: 80)
        .background(Color.yellow.opacity(0.2).clipShape(Circle()))
    }
}

Answer 1

这是使用 ZStack 和 scaleEffect 的解决方案。按下时缩小图标并在完成时恢复。与圆圈相反，按下时缩放并在完成时恢复。

struct AuraButtonView: View {
    // automatically resets gesture when complete
    @GestureState private var tapped = false
    // max size
    @State var fullSize : CGFloat = 72
    // size when button pressed
    @State var scale : CGFloat = 0.8

    // camera icon, shrink when pressed, restore on complete
    var icon : some View {
        Image(systemName: "camera")
            .font(.title)
            .scaleEffect(tapped ? CGSize(width: scale, height: scale) : CGSize(width: 1, height: 1))
            .animation(.easeInOut)
    }
    
    // yellow circle, grow when pressed, restore on complete
    var background : some View {
        Circle()
            .foregroundColor(tapped ? Color.yellow.opacity(0.2) : Color.clear)
            .frame(width: tapped ? fullSize : 0, height: tapped ? fullSize : 0, alignment: Alignment(horizontal: .center, vertical: .center))
            .animation(.easeInOut)
    }
    
    // stack the icon on the circle and use the zstack as the gesture
    var body: some View {
        ZStack(alignment: Alignment(horizontal: .center, vertical: .center), content: {
            background
            icon
        })
        .frame(width: fullSize, height: fullSize)
        .gesture(DragGesture(minimumDistance: 0)
                    .updating($tapped) { (_, tapped, _) in
                        tapped = true
                    })
    }
}

struct AuraButtonView_Previews: PreviewProvider {
    static var previews: some View {
        AuraButtonView()
    }
}

感谢@nils 的手势魔术