• 1、自定义preferenceKey

struct RectangleGeometrySizePreferenceKey: PreferenceKey {
    static var defaultValue: CGSize = .zero
    
    static func reduce(value: inout CGSize, nextValue: () -> CGSize) {
        value = nextValue()
    }
}

• 2、扩展View添加方法

extension View {
    func updateRectangleGeoSize(_ size: CGSize) -> some View {
        preference(key: RectangleGeometrySizePreferenceKey.self, value: size)
    }
}

• 3、使用例子

struct GeometryPreferenceBootCamp: View {
    // MARK: -  PROPERTY
    @State private var rectSize: CGSize = .zero
    // MARK: -  BODY
    var body: some View {
        VStack(spacing: 50) {
            Text("Hello")
                .frame(width: rectSize.width, height: rectSize.height)
                .background(Color.blue)
            
            
            HStack {
                Rectangle()
                
                GeometryReader { geo in
                    Rectangle()
                        .updateRectangleGeoSize(geo.size)
                }
                
                Rectangle()
            }
            .frame(height: 55)
        } //: VSTACK
        .onPreferenceChange(RectangleGeometrySizePreferenceKey.self) { value in
            self.rectSize = value
        }
    }
}

• 4、效果图

  
  
  16603830306264.jpg