ios – (Swift)UIPanGestureRecognizer在视图上工作正常,直到添

lazy var superView: UIView = {
    let cv = UIView()

    cv.backgroundColor = .gray
    cv.translatesAutoresizingMaskIntoConstraints = false
    cv.layer.cornerRadius = 5     
    cv.layer.masksToBounds = true     
    cv.isUserInteractionEnabled = true
    cv.addGestureRecognizer(UIPanGestureRecognizer(target: self,action: #selector(handlePan)))

    return cv
}()

这是我为它设置约束的地方：

// constraints for super view
func setupSuperView() {
    superView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
    superView.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true

    superView.widthAnchor.constraint(equalTo: view.widthAnchor,constant: -24).isActive = true
    superView.heightAnchor.constraint(equalTo: view.heightAnchor,constant: -200).isActive = true

    // ISSUE: For some reason,adding this subview with or without constraints screws up the pan functionality of the superview
    superView.addSubview(subView)
}

这是我添加到superView内部的子视图(我将其视为容器视图)：

lazy var subview: UIImageView = {
    let sv = UIImageView()

    sv.translatesAutoresizingMaskIntoConstraints = false
    sv.contentMode = .scaleAspectFill        

    return sv
}()

其约束：

// constraints for yes/no view within superview
func setupSubView() {
    subView.centerXAnchor.constraint(equalTo: superView.centerXAnchor).isActive = true
    subView.centerYAnchor.constraint(equalTo: superView.centerYAnchor).isActive = true
}

最后,这里是我为pan手势建立功能的地方：

// pan functionality for swiping on superview
func handlePan(gesture: UIPanGestureRecognizer) {

    guard let superview = gesture.view else {
        return
    }

    // point you are tapped on
    let point = gesture.translation(in: view)

    // reference for how far left or right of the center of the superview your pan is
    let xFromCenter = superview.center.x - view.center.x

    // allows the superview to move with your finger
    superview.center = CGPoint(x: view.center.x + point.x,y: view.center.y + point.y)

    // dragged right
    if xFromCenter > 0 {
        subView.image = #imageLiteral(resourceName: "yes")
        subView.tintColor = UIColor.green

    // else dragged left
    } else {
        subView.image = #imageLiteral(resourceName: "no")
        subView.tintColor = UIColor.red
    }

    // when you let go
    if gesture.state == UIGestureRecognizerState.ended {
        // animate superview back to center where it originally was
        UIView.animate(withDuration: 0.2) {

            superview.center = self.view.center
        }
    }

}

在我添加子视图之前(当我评论它时),pan手势在superview上运行得非常好.但是,当我将子视图限制在超视图的中心并尝试在视图控制器周围移动超视图时,它的行为很奇怪(只能向左移动,向右移动时不断向后移动).

非常感谢任何和所有的帮助.