SwiftUI按下按钮时定期运行代码；只需轻按一下即可运行不同的代码？

Question

我想做的是实现一个按钮，该按钮在按住期间每0.5秒运行一行特定的代码（可以无限期按住它，从而无限期地运行print语句）。我希望它在点击时具有不同的行为。这是代码：

struct ContentView: View {
@State var timeRemaining = 0.5
let timer = Timer.publish(every: 0.5, on: .main, in: .common).autoconnect()
@State var userIsPressing = false //detecting whether user is long pressing the screen

var body: some View {
    VStack {
       Image(systemName: "chevron.left").onReceive(self.timer) { _ in
           if self.userIsPressing == true {
             if self.timeRemaining > 0 {
                self.timeRemaining -= 0.5
              }
            //resetting the timer every 0.5 secdonds and executing code whenever //timer reaches 0

     if self.timeRemaining == 0 {
            print("execute this code")
            self.timeRemaining = 0.5
         }
        }
    }.gesture(LongPressGesture(minimumDuration: 0.5)
                   .onChanged() { _ in
                       //when longpressGesture started
                   self.userIsPressing = true
                   }
                   .onEnded() { _ in
                       //when longpressGesture ended
                   self.userIsPressing = false

                   }
                   )
           }
}
}

目前，这与我需要执行的操作相反；当我单击一次按钮时，上面的代码无限期地运行print语句，但是当我按下按钮时，它只会执行一次...如何解决此问题？

Answer 1

[这是解决方案-要获得连续按下，需要将长按手势与顺序拖动相结合，并在处理程序中添加计时器。

使用Xcode 11.4 / iOS 13.4测试

struct TestContinuousPress: View {
    @State private var timer = Timer.publish(every: Double.infinity, on: .main, in: .common).autoconnect()
    @State var userIsPressing = false //detecting whether user is long pressing the screen

    @GestureState var pressingState = false // will be true till tap hold
    var pressingGesture: some Gesture {
        LongPressGesture(minimumDuration: 0.5).sequenced(before:
              DragGesture(minimumDistance: 0, coordinateSpace:
              .local)).updating($pressingState) { value, state, transaction in
                switch value {
                    case .second(true, nil):
                        self.userIsPressing = true
                        self.timer = Timer.publish(every: 0.5, on: .main, in: .common).autoconnect()
                    default:
                        break
                }
            }.onEnded { _ in
                self.userIsPressing = false
                self.timer = Timer.publish(every: Double.infinity, on: .main, in: .common).autoconnect()
            }
    }

    var body: some View {
        VStack {
            Image(systemName: "chevron.left")

                .onReceive(self.timer) { _ in
                    print(">>>> pressing: \(Date())")
                }
            .gesture(TapGesture().onEnded {
                print("> just tap ")
            })
            .gesture(pressingGesture)
        }
    }
}