SwiftUI 按钮的 Aura 动画

问题描述

如何制作下面的动画？触摸按钮时出现灵气，整个盒子有点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()))
    }
}

解决方法

这是一个使用 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()
    }
}

Credit to @nils for the Gesture magic