在iOS中使用触摸绘制水平线或垂直线

问题描述：

我正在研究一个项目，我希望如果用户触摸沿水平方向移动，那么水平线应该绘制并且用户触摸沿垂直方向移动，然后垂直线应该绘制。请建议使用Swift的一些解决方案。我在下面试过。但是这是免费的。在iOS中使用触摸绘制水平线或垂直线

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) { 

     super.touchesBegan(touches, with: event) 

     let touch: AnyObject? = touches.first 
     let lastPoint = touch!.previousLocation(in: holderView) 
     path.move(to: CGPoint(x: lastPoint.x, y: lastPoint.y)) 

    } 

    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) { 

     super.touchesMoved(touches, with: event) 

     let touch: AnyObject? = touches.first 
     let currentPoint = touch!.location(in: holderView) 

     path.addLine(to: CGPoint(x: currentPoint.x, y: currentPoint.y)) 

     //Design path in layer 
     let shapeLayer = CAShapeLayer() 
     shapeLayer.path = path.cgPath 
     shapeLayer.strokeColor = UIColor.orange.cgColor 
     shapeLayer.lineWidth = 20.0 

     holderView.layer.addSublayer(shapeLayer) 

} 

    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) { 

     super.touchesEnded(touches, with: event) 
     path=UIBezierPath() 
    }

可以通过这个链接http://stackoverflow.com/questions/4669490/how-to-draw-line-on-touch-event –

什么，如果用户触摸屏幕，并创建一个曲线路径点数？ –

太多未知数！你的代码说：“有一条更加缓慢的路径，当触摸开始时，跳到触摸位置，当触摸移动时，画线到新的位置并在新的子图层中显示结果，当触摸结束时，创建一个新的贝塞尔路径” 。子层逻辑看起来效率极低（创建数百个部分重复的子层），而且更复杂的路径创建似乎不必要地倒退，但除此之外。鉴于上述逻辑的解释，你能否澄清你想达到的目标？ – Baglan

答

试试这个。

class DrawingView: UIView { 
    var path = UIBezierPath() 
    var initialLocation = CGPoint.zero 
    var finalLocation = CGPoint.zero 
    var shapeLayer = CAShapeLayer() 

    override func awakeFromNib() { 
     super.awakeFromNib() 
     setupView() 
    } 

    override init(frame: CGRect) { 
     super.init(frame: frame) 
     setupView() 
    } 

    required init?(coder aDecoder: NSCoder) { 
     fatalError("init(coder:) has not been implemented") 
    } 

    func setupView(){ 
     self.layer.addSublayer(shapeLayer) 
     self.shapeLayer.lineWidth = 20 
     self.shapeLayer.strokeColor = UIColor.blue.cgColor 
    } 


    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) { 
     super.touchesBegan(touches, with: event) 
     if let location = touches.first?.location(in: self){ 
      initialLocation = location 
     } 
    } 

    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) { 
     super.touchesMoved(touches, with: event) 

     if let location = touches.first?.location(in: self){ 
      let dx = location.x - initialLocation.x 
      let dy = location.y - initialLocation.y 

      finalLocation = abs(dx) > abs(dy) ? CGPoint(x: location.x, y: initialLocation.y) : CGPoint(x: initialLocation.x, y: location.y) 

      path.removeAllPoints() 
      path.move(to: initialLocation) 
      path.addLine(to: finalLocation) 

      shapeLayer.path = path.cgPath 

     } 
    } 
}

在iOS中使用触摸绘制水平线或垂直线

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