UISwipeGestureRecognizer 不适用于呈现的 VC 和视图

Question

层次结构：

• MainVC 调用present(GameVC, animated: true, completion: nil)

  let vc = self.storyboard?.instantiateViewController(withIdentifier: "GameVC") as! GameVC self.present(vc, animated: true, completion: nil)

• GameVC 具有覆盖整个 VC 的 GameView（UIView 的子类）

在GameView的初始化程序中，我有这段代码来配置滑动手势：

let leftGesture = UISwipeGestureRecognizer(target: self, action: #selector(leftSwipe))
leftGesture.direction = .left
self.addGestureRecognizer(leftGesture)

let rightGesture = UISwipeGestureRecognizer(target: self, action: #selector(rightSwipe))
rightGesture.direction = .right
self.addGestureRecognizer(rightGesture)

let downGesture = UISwipeGestureRecognizer(target: self, action: #selector(downSwipe))
downGesture.direction = .down
self.addGestureRecognizer(downGesture)

对应的选择器：

@objc func downSwipe() {
    //code
}

@objc func leftSwipe() {
    //code
}

@objc func rightSwipe() {
    //code
}

选择器没有被调用。但是，当我将 GameVC 设置为正在显示的初始 VC 时（通过将情节提要箭头拖到 GameVC 上），手势按预期工作。这让我认为调用 present() 可能'已经搞乱了手势操作的层次结构，但我不太确定。

Answer 1

您必须表明您的手势可以通过提供相应的委托方法同时处理。

下面的演示代码可以使用上面的代码。使用 Xcode 11.4 / iOS 13.4 测试

class GameView: UIView {
}

// in Storyboard just empty view of above custom GameView
class GameVC: UIViewController, UIGestureRecognizerDelegate {

    override func viewDidLoad() {
        super.viewDidLoad()

        let leftGesture = UISwipeGestureRecognizer(target: self, action: #selector(leftSwipe))
        leftGesture.direction = .left
        leftGesture.delegate = self
        self.view.addGestureRecognizer(leftGesture)

        let rightGesture = UISwipeGestureRecognizer(target: self, action: #selector(rightSwipe))
        rightGesture.direction = .right
        rightGesture.delegate = self
        self.view.addGestureRecognizer(rightGesture)

        let downGesture = UISwipeGestureRecognizer(target: self, action: #selector(downSwipe))
        downGesture.direction = .down
        downGesture.delegate = self
        self.view.addGestureRecognizer(downGesture)

    }

    // allows own view gestures to run with system originated simultaneously
    func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
        true
    }

    @objc func downSwipe() {
        print(">> down swipe")
    }

    @objc func leftSwipe() {
        print(">> left swipe")
    }

    @objc func rightSwipe() {
        print(">> right swipe")
    }
}

// Initial VC, in storyboard contains only button linked to below showGame action
class ViewController: UIViewController {

    @IBAction func showGame(_ sender: Any) {
        let vc = self.storyboard?.instantiateViewController(withIdentifier: "GameVC") as! GameVC
        self.present(vc, animated: true, completion: nil)
    }
}