Ios 绘制线条，触摸位置缩小并淡入背景Swift 3.0

我在Swift 3.0上遇到了一个奇怪的错误，我成功地在UIView中绘制了UIImageView，但是，当我绘制之前绘制的线时，它开始褪色并收缩到UIImageView的顶部，并且变得非常模糊，如所附图像所示。

如能提供任何帮助/指导，我将不胜感激

class DrawView: UIView {
    var drawArea: UIImageView!
    var clearDrawArea: UIButton!
    var lastTouch = CGPoint.zero

    init(){
        super.init(frame: CGRect(x: UIScreen.main.bounds.width*0.135, y:UIScreen.main.bounds.height*0.05, width: UIScreen.main.bounds.width*0.8, height: UIScreen.main.bounds.height*0.9))
        drawArea = UIImageView(frame: CGRect(x: self.frame.origin.x, y: self.frame.origin.y, width: self.bounds.width*0.9, height: self.bounds.height*0.86))
        drawArea.backgroundColor = UIColor.white

        let buttonWidth = self.bounds.width*0.2
        let buttonHeight = self.bounds.height*0.1
        clearDrawArea = UIButton(frame: CGRect(x: (self.bounds.width*0.61)-(buttonWidth/2), y: self.bounds.height*0.94, width: buttonWidth, height: buttonHeight))
        clearDrawArea.setTitle("Clear Draw Area", for: .normal)
        clearDrawArea.backgroundColor = UIColor(red: 49/255, green: 200/255, blue: 134/255, alpha: 255)
        clearDrawArea.addTarget(self, action: #selector(resetImage), for: .touchUpInside)

        self.addSubview(clearDrawArea)
        self.addSubview(drawArea)

    }

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

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

        if let firstTouch = touches.first{

            lastTouch = firstTouch.location(in: drawArea)
        }

    }
    func drawLines(_ from: CGPoint, to: CGPoint){
        UIGraphicsBeginImageContext(drawArea.frame.size)
        let context = UIGraphicsGetCurrentContext()

        context?.move(to: CGPoint(x: from.x, y: from.y))
        context?.addLine(to: CGPoint(x: to.x, y: to.y))

        context?.setLineCap(.round)
        context?.setLineWidth(3)
        context?.setStrokeColor(UIColor.black.cgColor)

        context?.strokePath()

        drawArea.image?.draw(in: drawArea.bounds)
        drawArea.image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
    }
    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {


        if let firstTouch = touches.first{
            let touchLocation = firstTouch.location(in: drawArea)
            drawLines(lastTouch, to: touchLocation)

            lastTouch = touchLocation
        }
    }

    func resetImage(){

        drawArea.image = nil            
    }
}

类DrawView:UIView{
var绘图区域：UIImageView！
var clearDrawArea:UIButton！
var lastTouch=CGPoint.zero
init（）{
super.init（帧：CGRect（x:UIScreen.main.bounds.width*0.135，y:UIScreen.main.bounds.height*0.05，width:UIScreen.main.bounds.width*0.8，height:UIScreen.main.bounds.height*0.9））
drawArea=UIImageView（帧：cRect（x:self.frame.origin.x，y:self.frame.origin.y，宽度：self.bounds.width*0.9，高度：self.bounds.height*0.86））
drawArea.backgroundColor=UIColor.white
let buttonWidth=self.bounds.width*0.2
let buttonHeight=自身边界高度*0.1
clearDrawArea=UIButton（边框：CGRect（x:（自边界.宽度*0.61）-（按钮宽度/2），y:自边界.高度*0.94，宽度：按钮宽度，高度：按钮宽度））
clearDrawArea.setTitle（“清除绘图区域”，用于：。正常）
clearDrawArea.backgroundColor=UIColor（红色：49/255，绿色：200/255，蓝色：134/255，alpha:255）
clearDrawArea.addTarget（self，action:#选择器（resetImage），for:.touchUpInside）
self.addSubview（clearDrawArea）
self.addSubview（绘图区域）
}
必需的初始化？（编码器aDecoder:NSCoder）{
fatalError（“初始化（编码者：）尚未实现”）
}
覆盖func TouchesBegind（Touchs:Set，带有事件：UIEvent？）{
如果let firstTouch=touch.first{
lastTouch=firstTouch.位置（在：绘图区）
}
}
func绘图线（从：CGPoint到：CGPoint）{
UIGraphicsBeginImageContext（drawArea.frame.size）
let context=UIGraphicsGetCurrentContext（）
上下文？.move（到：CGPoint（x:from.x，y:from.y））
context？.addLine（to:CGPoint（x:to.x，y:to.y））
上下文？.setLineCap（.round）
上下文？.setLineWidth（3）
上下文？.setStrokeColor（UIColor.black.cgColor）
上下文？.strokePath（）
drawArea.image？绘制（in:drawArea.bounds）
drawArea.image=UIGraphicsGetImageFromCurrentImageContext（）
UIGraphicsSendImageContext（）
}
覆盖功能触摸移动（touchs:Set，带有事件：UIEvent？）{
如果let firstTouch=touch.first{
让touchLocation=firstTouch.location（在：绘图区域中）
抽绳（lastTouch，至：touchLocation）
lastTouch=触摸位置
}
}
func resetImage（）{
drawArea.image=nil
}
}

稍微更改了代码，请尝试以下操作

class DrawView: UIView {
var drawArea: UIImageView!
var clearDrawArea: UIButton!
var lastTouch = CGPoint.zero
let pathAnimation: CABasicAnimation = CABasicAnimation(keyPath:"animation")
let tempPathLayer: CAShapeLayer = CAShapeLayer()
var lineLayer:CAShapeLayer=CAShapeLayer()
init(){
    super.init(frame: CGRect(x: UIScreen.main.bounds.width*0.135, y:UIScreen.main.bounds.height*0.05, width: UIScreen.main.bounds.width*0.8, height: UIScreen.main.bounds.height*0.9))
    drawArea = UIImageView(frame: CGRect(x: self.frame.origin.x, y: self.frame.origin.y, width: self.bounds.width*0.9, height: self.bounds.height*0.86))
    drawArea.backgroundColor = UIColor.white

    let buttonWidth = self.bounds.width*0.2
    let buttonHeight = self.bounds.height*0.1
    clearDrawArea = UIButton(frame: CGRect(x: (self.bounds.width*0.61)-(buttonWidth/2), y: self.bounds.height*0.94, width: buttonWidth, height: buttonHeight))
    clearDrawArea.setTitle("Clear Draw Area", for: .normal)
    clearDrawArea.backgroundColor = UIColor(red: 49/255, green: 200/255, blue: 134/255, alpha: 255)
    clearDrawArea.addTarget(self, action: #selector(resetImage), for: .touchUpInside)

    self.addSubview(clearDrawArea)
    self.addSubview(drawArea)

}

required init?(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)

    //fatalError("init(coder:) has not been implemented")
}

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

    if let firstTouch = touches.first{

        lastTouch = firstTouch.location(in: drawArea)
    }

}
func drawLines(_ from: CGPoint, to: CGPoint){
    UIGraphicsBeginImageContext(drawArea.frame.size)

    //let context = UIGraphicsGetCurrentContext()
    let tempPath: UIBezierPath = UIBezierPath()
    var lineLayer:CAShapeLayer=CAShapeLayer()
    tempPath.move(to: from)
    tempPath.addLine(to: to)
    let strokeColor = UIColor.red
    UIColor.blue.setFill()
    strokeColor.setStroke()

    let tempPathLayer: CAShapeLayer = CAShapeLayer()
    tempPathLayer.frame = self.bounds
    tempPathLayer.position=self.layer.position
    tempPathLayer.strokeColor = UIColor.green.cgColor
    tempPathLayer.fillColor = UIColor.red.cgColor
    tempPathLayer.lineWidth = 1.0
    tempPathLayer.path = tempPath.cgPath
    lineLayer=tempPathLayer
    pathAnimation.beginTime=CACurrentMediaTime()
    pathAnimation.duration = 2
    pathAnimation.fromValue = NSNumber(value: 0.0)
    pathAnimation.toValue = NSNumber(value:1.0)

    lineLayer.add(pathAnimation, forKey: "animation")
    self.layer.addSublayer(lineLayer)

    drawArea.image?.draw(in: drawArea.bounds)
    drawArea.image = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
}

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


    if let firstTouch = touches.first{
        let touchLocation = firstTouch.location(in: drawArea)
        drawLines(lastTouch, to: touchLocation)

        lastTouch = touchLocation
    }
}

func resetImage(){

    drawArea.image = nil            
}

类DrawView:UIView{
var绘图区域：UIImageView！
var clearDrawArea:UIButton！
var lastTouch=CGPoint.zero
让路径动画：cabasicanition=cabasicanition（关键路径：“动画”）
让tempPathLayer:CAShapeLayer=CAShapeLayer（）
变量lineLayer:CAShapeLayer=CAShapeLayer（）
init（）{
super.init（帧：CGRect（x:UIScreen.main.bounds.width*0.135，y:UIScreen.main.bounds.height*0.05，width:UIScreen.main.bounds.width*0.8，height:UIScreen.main.bounds.height*0.9））
drawArea=UIImageView（帧：cRect（x:self.frame.origin.x，y:self.frame.origin.y，宽度：self.bounds.width*0.9，高度：self.bounds.height*0.86））
drawArea.backgroundColor=UIColor.white
let buttonWidth=self.bounds.width*0.2
let buttonHeight=自身边界高度*0.1
clearDrawArea=UIButton（边框：CGRect（x:（自边界.宽度*0.61）-（按钮宽度/2），y:自边界.高度*0.94，宽度：按钮宽度，高度：按钮宽度））
clearDrawArea.setTitle（“清除绘图区域”，用于：。正常）
clearDrawArea.backgroundColor=UIColor（红色：49/255，绿色：200/255，蓝色：134/255，alpha:255）
clearDrawArea.addTarget（self，action:#选择器（resetImage），for:.touchUpInside）
self.addSubview（clearDrawArea）
self.addSubview（绘图区域）
}
必需的初始化？（编码器aDecoder:NSCoder）{
super.init（编码者：aDecoder）
//fatalError（“初始化（编码者：）尚未实现”）
}
覆盖func TouchesBegind（Touchs:Set，带有事件：UIEvent？）{
如果let firstTouch=touch.first{
lastTouch=firstTouch.位置（在：绘图区）
}
}
func绘图线（从：CGPoint到：CGPoint）{
UIGraphicsBeginImageContext（drawArea.frame.size）
//let context=UIGraphicsGetCurrentContext（）
让tempPath:UIBezierPath=UIBezierPath（）
变量lineLayer:CAShapeLayer=CAShapeLayer（）
tempPath.move（到：从）
tempPath.addLine（to:to）
让strokeColor=UIColor.red
UIColor.blue.setFill（）
strokeColor.setStroke（）
让tempPathLayer:CAShapeLayer=CAShapeLayer（）
tempPathLayer.frame=self.bounds
tempPathLayer.position=self.layer.position
tempPathLayer.strokeColor=UIColor.green.cgColor
tempPathLayer.fillColor=UIColor.red.cgColor
tempPathLayer.lineWidth=1.0
tempPathLayer.path=tempPath.cgPath
lineLayer=tempPathLayer
pathAnimation.beginTime=CACurrentMediaTime（）
pathAnimation.duration=2
pathAnimation.fromValue=NSNumber（值：0.0）
pathAnimation.toValue=NSNumber（值：1.0）
lineLayer.add（路径动画，forKey：“动画”）
self.layer.addSublayer（lineLayer）
drawArea.image？绘制（in:drawArea.bounds）
drawArea.image=UIGraphicsGetImageFromCurrentImageContext（）
UIGraphicsSendImageContext（）
}
覆盖功能触摸移动（touchs:Set，带有事件：UIEvent？）{
如果let firstTouch=touch.first{
让touchLocation=firstTouch.location（在：绘图区域中）
抽绳（lastTouch，至：touchLocation）
lastTouch=触摸位置
}
}
func resetImage（）{
drawArea.image=nil
}

---

}我终于让它正常工作了。我利用了你的想法，改用贝塞尔路径

class DrawView: UIView {
var drawArea: UIImageView!
var clearDrawArea: UIButton!
var lastTouch = CGPoint.zero
var context: CGContext!
var path: UIBezierPath!
init(){
    context = UIGraphicsGetCurrentContext()
    path = UIBezierPath()
    super.init(frame: CGRect(x: UIScreen.main.bounds.width*0.135, y:UIScreen.main.bounds.height*0.05, width: UIScreen.main.bounds.width*0.8, height: UIScreen.main.bounds.height*0.9))
    drawArea = UIImageView(frame: CGRect(x: self.frame.origin.x, y: self.frame.origin.y, width: self.bounds.width*0.9, height: self.bounds.height*0.86))
    drawArea.backgroundColor = UIColor.white

    let buttonWidth = self.bounds.width*0.2
    let buttonHeight = self.bounds.height*0.1
    clearDrawArea = UIButton(frame: CGRect(x: (self.bounds.width*0.61)-(buttonWidth/2), y: self.bounds.height*0.94, width: buttonWidth, height: buttonHeight))
    clearDrawArea.setTitle("Clear Draw Area", for: .normal)
    clearDrawArea.backgroundColor = UIColor(red: 49/255, green: 200/255, blue: 134/255, alpha: 255)
    clearDrawArea.addTarget(self, action: #selector(resetImage), for: .touchUpInside)

    self.addSubview(clearDrawArea)
    self.addSubview(drawArea)

}

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

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

    if let firstTouch = touches.first{

        lastTouch = firstTouch.location(in: drawArea)
    }

}
func drawLines(_ from: CGPoint, to: CGPoint){
    UIGraphicsBeginImageContext(drawArea.frame.size)

    path.move(to: CGPoint(x: from.x, y: from.y))
    path.addLine(to: CGPoint(x: to.x, y: to.y))

    UIColor.black.setStroke()
    path.lineWidth = 3
    path.stroke()

    context?.saveGState()
    context?.addPath(path.cgPath)
    context?.closePath()
    context?.restoreGState()

    drawArea.image = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {


    if let firstTouch = touches.first {
        let touchLocation = firstTouch.location(in: drawArea)
        drawLines(lastTouch, to: touchLocation)

        lastTouch = touchLocation
    }
}

func resetImage(){
    path.removeAllPoints()
    drawArea.image = nil            
}