ios - 在swiftui中按钮的触摸 Action 播放音频

Question

我想在按下按钮时(一旦单击它)而不是在 SwiftUI 中的触摸释放时播放音频。我该如何实现？
我的代码看起来像这样:

struct PressedButtonStyle: ButtonStyle {
    let touchDown: () -> ()
    func makeBody(configuration: Self.Configuration) -> some View {
        configuration.label
            .foregroundColor(configuration.isPressed ? Color.gray : Color.blue)
            .background(configuration.isPressed ? self.handlePressed() : Color.clear)
    }

    private func handlePressed() -> Color {
        touchDown()
        return Color.clear
    }
}
 

struct DemoPressedButton: View {
    @State var audioPlayer: AVAudioPlayer!

    var body: some View {
        Button("Demo") {
            print(">> tap up")
        }
        .buttonStyle(PressedButtonStyle {
            print(">> tap down")
            let sound = Bundle.main.path(forResource: "filename", ofType: "wav")
            self.audioPlayer = try! AVAudioPlayer(contentsOf: URL(fileURLWithPath: sound!)) // receives warning about changing state while updating view
            self.audioPlayer.play() // breaks 
        })
    }
}

调用 self.audioPlayer.play() 时代码中断。
自定义着陆代码来自此链接: SwiftUI button action as soon as button is clicked not on click release

Answer 1

这是一个可能的方法的演示。使用 Xcode 11.4/iOS 13.4 测试
注意:您应该继续引用 AVAudioPlayer当它正在播放并更好地跟踪它的状态时，所以这更适合在一些帮助类(如 View 模型)中执行

class PlayViewModel {
    private var audioPlayer: AVAudioPlayer!
    func play() {
        let sound = Bundle.main.path(forResource: "filename", ofType: "wav")
        self.audioPlayer = try! AVAudioPlayer(contentsOf: URL(fileURLWithPath: sound!))
        self.audioPlayer.play()
    }
}

struct DemoPressedButton: View {
    let vm = PlayViewModel()

    var body: some View {
        Button("Demo") {
            print(">> tap up")
        }
        .buttonStyle(PressedButtonStyle {
            print(">> tap down")
            self.vm.play()
        })
    }
}