如何将平移手势识别器限制在捏手势发生时？

Question

当用户处于捏合手势的过程中时，您如何只接受平移手势？ 换句话说，我想避免提供单指平移手势。

@IBAction func pinchPiece(_ pinchGestureRecognizer: UIPinchGestureRecognizer) {
    guard pinchGestureRecognizer.state == .began || pinchGestureRecognizer.state == .changed,
          let piece = pinchGestureRecognizer.view else {
            // After pinch releases, zoom back out.
            if pinchGestureRecognizer.state == .ended {
              UIView.animate(withDuration: 0.3, animations: {
                pinchGestureRecognizer.view?.transform = CGAffineTransform.identity
              })
            }
            return
    }
    adjustAnchor(for: pinchGestureRecognizer)
    
    let scale = pinchGestureRecognizer.scale
    piece.transform = piece.transform.scaledBy(x: scale, y: scale)
    pinchGestureRecognizer.scale = 1 // Clear scale so that it is the right delta next time.
}

@IBAction func panPiece(_ panGestureRecognizer: UIPanGestureRecognizer) {
    guard panGestureRecognizer.state == .began || panGestureRecognizer.state == .changed,
          let piece = panGestureRecognizer.view else {
        return
    }
    let translation = panGestureRecognizer.translation(in: piece.superview)
    piece.center = CGPoint(x: piece.center.x + translation.x, y: piece.center.y + translation.y)
    panGestureRecognizer.setTranslation(.zero, in: piece.superview)
}

public func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer,
                            shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
    true
}

Answer 1

你可以使用require(toFail:)

例如，如果您有两个手势tap和swipe

轻扫手势是轻击之后的线性移动，而轻击只是轻击——我们需要确保轻扫手势在检查轻击手势之前绝对没有被识别器识别。

iOS 通常在这方面做得相当好，但没有必要让它靠运气：如果你在点击手势识别器上调用 require(toFail:) ，传入滑动识别器，iOS 肯定会确保他们不会竞争：

let swipe = UISwipeGestureRecognizer(target: self, action: #selector(executeSwipe))
let tap = UITapGestureRecognizer(target: self, action: #selector(executeTap))

view.addGestureRecognizer(swipe)
view.addGestureRecognizer(tap)

tap.require(toFail: swipe)

Answer 2

您可以轻松启用和禁用手势。 当它开始捏时禁用平移手势并在结束捏时启用它。 当它开始平移时，禁用捏合手势并在结束平移时启用它。

@IBAction func pinchPiece(_ pinchGestureRecognizer: UIPinchGestureRecognizer) {
    guard pinchGestureRecognizer.state == .began || pinchGestureRecognizer.state == .changed,
          let piece = pinchGestureRecognizer.view else {
             yourPangesture.isEnable = false // Disable Pangesture
            // After pinch releases, zoom back out.
            if pinchGestureRecognizer.state == .ended {
              UIView.animate(withDuration: 0.3, animations: {
                pinchGestureRecognizer.view?.transform = CGAffineTransform.identity
              })
            }
            return
    }
    if pinchGestureRecognizer.state == .end {
         yourPangesture.isEnable = true  // Enabling again
    }
    adjustAnchor(for: pinchGestureRecognizer)
    
    let scale = pinchGestureRecognizer.scale
    piece.transform = piece.transform.scaledBy(x: scale, y: scale)
    pinchGestureRecognizer.scale = 1 // Clear scale so that it is the right delta next time.
}

对 panPiece 函数执行相同的操作。