Swift UI - 我正在尝试更改背景。它在函数 buttonPressed() 下给我一个错误

Question

这是我正在做的一个项目，基本上可以让我有一个欢迎页面。单击 'click here' 后，按下的按钮应该会使新背景充满新颜色（创建新场景）...我希望稍后添加更多内容。

import SwiftUI

struct ContentView: View {
    
    // defined global variables in a function
    @State var backgroundColor: Color = Color.red
    
    var body: some View {
        ZStack {
            // background called
            backgroundColor
                .edgesIgnoringSafeArea(.all)

            // content
            contentLayer
            }
        }

    var contentLayer: some View {
            // content
        VStack {
            Text("Welcome to newsapptest!")
                .font(.largeTitle)
                
                Button(action: {
                    buttonPressed()
                }, label: {
                    Text("Click here to continue to the app!")
                        .font(.headline)
                        .foregroundColor(.white)
                        .padding()
                        .background(Color.black)
                        .cornerRadius(10)
                })
            }
        }
    }
    
    func buttonPressed() {
        backgroundColor = .blue

backgroundColor = .blue 给我一个问题，说它不在我的范围内。我该如何解决这个问题？

}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

Answer 1

如果您格式化您的代码（select 并使用 ctrl-i），您会发现您的 buttonPressed 函数实际上在之外你的 ContentView 结构。将它移到里面，它会正确编译：

struct ContentView: View {
    
    // defined global variables in a function
    @State var backgroundColor: Color = Color.red
    
    var body: some View {
        ZStack {
            // background called
            backgroundColor
                .edgesIgnoringSafeArea(.all)
            
            // content
            contentLayer
        }
    }
    
    var contentLayer: some View {
        // content
        VStack {
            Text("Welcome to newsapptest!")
                .font(.largeTitle)
            
            Button(action: {
                buttonPressed()
            }, label: {
                Text("Click here to continue to the app!")
                    .font(.headline)
                    .foregroundColor(.white)
                    .padding()
                    .background(Color.black)
                    .cornerRadius(10)
            })
        }
    }
    
    func buttonPressed() {
        backgroundColor = .blue
    }
}

Swift UI - 我正在尝试更改背景。它在函数 buttonPressed() 下给我一个错误

Swift UI - I am trying to change the background. It is giving me an error under the function buttonPressed()

ios

swift

iphone

swiftui

applescript