使用 CGPath 创建一个子视图，而不是在该子视图上添加 UIPanGestureRecognizer

Question

我看到了几个关于向子视图添加 GestureRecognzier 的答案，但我的问题是我事先没有可用的子视图框架。我正在绘制一个 CGPath 并且在 Touches Ended 方法中，我想创建一个新的 subView，其框架等于 CGPath 边界框。在那之后，我想用 PanGestureRecognizer 拖那个 subView。我正在尝试实现 Evernote crop 功能，用户可以在其中选择特定的视图区域并将其移动到其他位置。这是该解决方案的正确方法吗？

Answer 1

不太明白UIGestureRecognizer和.frame之间的关系。你可以简单地添加 UIGestureRecognizer 到对象，一旦它的初始化工作完成。尝试在绘制子视图后直接在TouchEnd方法中添加手势。

import UIKit

class GestureResearchVC: UIViewController{

    var subViewByCGPath: UIView?

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    func createSubView(){
        //creat subview
        subViewByCGPath = UIView(frame: CGRect(x: 100, y: 100, width: 100, height: 100))
        subViewByCGPath?.backgroundColor = UIColor.yellow
        let circlePath = UIBezierPath(arcCenter: CGPoint(x: 50,y: 50), radius: CGFloat(20), startAngle: CGFloat(0), endAngle:CGFloat(M_PI * 2), clockwise: true)

        let shapeLayer = CAShapeLayer()
        shapeLayer.path = circlePath.cgPath
        shapeLayer.strokeColor = UIColor.red.cgColor

        subViewByCGPath?.layer.addSublayer(shapeLayer)
        self.view.addSubview(subViewByCGPath!)

        //add pan gesture to subViewByCGPath
        let gesture = UIPanGestureRecognizer(target: self, action: #selector(panGestureAction(rec:)))
        subViewByCGPath?.addGestureRecognizer(gesture)
}

    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
        if subViewByCGPath == nil {
            print("touch end once")
            createSubView()
        }else{
            print("touch end repeatedly")
        }
    }

    func panGestureAction(rec: UIPanGestureRecognizer){
        print("pannnnnnn~")
        let transPoint = rec.translation(in: self.view)
        let x = rec.view!.center.x + transPoint.x
        let y = rec.view!.center.y + transPoint.y

        rec.view!.center = CGPoint(x: x, y: y)
        rec.setTranslation(CGPoint(x: 0, y: 0), in: self.view)

        //distinguish state
        switch rec.state {
            case .began:
                print("began")
            case .changed:
                print("changed")
            case .ended:
                print("ended")
            default:
                print("???")
        }
    }
}

使用 CGPath 创建一个子视图，而不是在该子视图上添加 UIPanGestureRecognizer

Create a subView using CGPath and than adding UIPanGestureRecognizer on that subview

ios

swift3

subview

uipangesturerecognizer

evernote