在 SwiftUI 中处理双重和三重手势识别器

Question

我正在尝试区分 SwiftUI 中的双击和三次点击手势识别器。在基于故事板的应用程序中，可以使用 来完成UIGestureRecognizerDelegate，但在 SwiftUI 中我还没有找到任何解决方案。

笔记：

以下不起作用：

.onTapGesture(count: 3) {
    print("Triple Tap!")
}
.onTapGesture(count: 2) {
    print("Double Tap!")
}

Answer 1

这是正确的方法，如果我自己可以这么说的话！

在 iOS 14.4.2、Xcode 12.5 beta 3 上测试。

使用此点击手势，仅点击一次后不会发生任何事情，双击后您将"double tap"在控制台中看到打印，三次或多次点击后您将"triple tap"在控制台中看到打印。

struct ContentView: View {
    var tapGesture: some Gesture {
        SimultaneousGesture(TapGesture(count: 2), TapGesture(count: 3))
            .onEnded { gestureValue in
                if gestureValue.second != nil {
                    print("triple tap!")
                } else if gestureValue.first != nil {
                    print("double tap!")
                }
            }
    }
    
    var body: some View {
        Text("Hello World!")
            .gesture(tapGesture)
    }
}

Answer 2

为了拥有一些适合项目中每个人需求的多手势，Apple 没有提供比普通手势更好的功能，将它们混合在一起以达到所需的手势有时会很棘手，这是一个救赎，工作没有问题或错误！

一个名为tapCountRecognizer的自定义零问题手势，我们可以将其应用到任何视图。用于同时进行单次、两次和三次点击手势协同工作。

请注意，您也可以像这样使用，仅适用于doubleTap和TripleTap：

.tapCountRecognizer(tapSensitivity: 250, doubleTapAction: doubleTapAction, tripleTapAction: tripleTapAction)

或者：

.tapCountRecognizer(doubleTapAction: doubleTapAction, tripleTapAction: tripleTapAction)

import SwiftUI

struct ContentView: View {
    
    var body: some View {
        
        Circle()
            .fill(Color.red)
            .frame(width: 100, height: 100, alignment: .center)
            .tapCountRecognizer(tapSensitivity: 250, singleTapAction: singleTapAction, doubleTapAction: doubleTapAction, tripleTapAction: tripleTapAction)
            .shadow(radius: 10)
            .statusBar(hidden: true)
        
    }
    
    func singleTapAction() { print("singleTapAction") }
    
    func doubleTapAction() { print("doubleTapAction") }
    
    func tripleTapAction() { print("tripleTapAction") }
    
}

struct TapCountRecognizerModifier: ViewModifier {
    
    let tapSensitivity: Int
    let singleTapAction: (() -> Void)?
    let doubleTapAction: (() -> Void)?
    let tripleTapAction: (() -> Void)?
    
    
    init(tapSensitivity: Int = 250, singleTapAction: (() -> Void)? = nil, doubleTapAction: (() -> Void)? = nil, tripleTapAction: (() -> Void)? = nil) {
        
        self.tapSensitivity  = ((tapSensitivity >= 0) ? tapSensitivity : 250)
        self.singleTapAction = singleTapAction
        self.doubleTapAction = doubleTapAction
        self.tripleTapAction = tripleTapAction
        
    }
    
    @State private var tapCount: Int = Int()
    @State private var currentDispatchTimeID: DispatchTime = DispatchTime.now()
    
    func body(content: Content) -> some View {

        return content
            .gesture(fundamentalGesture)
        
    }
    
    var fundamentalGesture: some Gesture {
        
        DragGesture(minimumDistance: 0.0, coordinateSpace: .local)
            .onEnded() { _ in tapCount += 1; tapAnalyzerFunction() }
        
    }
    
    
    
    func tapAnalyzerFunction() {
        
        currentDispatchTimeID = dispatchTimeIdGenerator(deadline: tapSensitivity)
        
        if tapCount == 1 {
            
            let singleTapGestureDispatchTimeID: DispatchTime = currentDispatchTimeID
            
            DispatchQueue.main.asyncAfter(deadline: singleTapGestureDispatchTimeID) {

                if (singleTapGestureDispatchTimeID == currentDispatchTimeID) {

                    if let unwrappedSingleTapAction: () -> Void = singleTapAction { unwrappedSingleTapAction() }

                    tapCount = 0
                    
                }
                
            }
            
        }
        else if tapCount == 2 {
            
            let doubleTapGestureDispatchTimeID: DispatchTime = currentDispatchTimeID
            
            DispatchQueue.main.asyncAfter(deadline: doubleTapGestureDispatchTimeID) {
                
                if (doubleTapGestureDispatchTimeID == currentDispatchTimeID) {
 
                    if let unwrappedDoubleTapAction: () -> Void = doubleTapAction { unwrappedDoubleTapAction() }
                    
                    tapCount = 0
                    
                }
                
            }
            
        }
        else  {
            
            
            if let unwrappedTripleTapAction: () -> Void = tripleTapAction { unwrappedTripleTapAction() }
            
            tapCount = 0
            
        }
        
    }
    
    func dispatchTimeIdGenerator(deadline: Int) -> DispatchTime { return DispatchTime.now() + DispatchTimeInterval.milliseconds(deadline) }
    
}

extension View {
    
    func tapCountRecognizer(tapSensitivity: Int = 250, singleTapAction: (() -> Void)? = nil, doubleTapAction: (() -> Void)? = nil, tripleTapAction: (() -> Void)? = nil) -> some View {
        
        return self.modifier(TapCountRecognizerModifier(tapSensitivity: tapSensitivity, singleTapAction: singleTapAction, doubleTapAction: doubleTapAction, tripleTapAction: tripleTapAction))
        
    }
    
}