Ios 如何在swift中在图像上自由绘制/涂鸦线条？

我已经搜索了这个案例的解决方案，但在互联网上没有找到。我想画/涂鸦一条线，比如snapchat或whatsapp状态，允许用户自由绘制。我发现了一个类似的教程，但它只是在本教程的UIView上绘制的：

我想允许用户自由地绘制他们从图像库/相机中拾取的图像，然后将结果保存回UIImage

UIView上涂鸦的源代码（第一张图片）如下所示

首先，创建自定义视图

class DrawView : ShadowView {

    var isDrawing = false
    var lastPoint : CGPoint!
    var strokeColor : CGColor! = UIColor.black.cgColor
    var strokes = [Stroke]()


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

        guard !isDrawing else { return }
        isDrawing = true

        guard let touch = touches.first else {return}
        let currentPoint = touch.location(in: self)
        lastPoint = currentPoint
        print(currentPoint)


    }



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


        guard isDrawing else { return}

        guard let touch = touches.first else {return}
        let currentPoint = touch.location(in: self)
        let stroke = Stroke(startPoint: lastPoint, endPoint: currentPoint, strokeColor: strokeColor)
        strokes.append(stroke)
        lastPoint = currentPoint

        setNeedsDisplay()


        print(currentPoint)
    }




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

         guard isDrawing else { return}
         isDrawing = false 

        guard let touch = touches.first else {return}

        let currentPoint = touch.location(in: self)
        let stroke = Stroke(startPoint: lastPoint, endPoint: currentPoint, strokeColor: strokeColor)
        strokes.append(stroke)

        setNeedsDisplay() 

        lastPoint = nil
        print(currentPoint)

    }


    override func draw(_ rect: CGRect) {

        let context = UIGraphicsGetCurrentContext()
        context?.setLineWidth(5) 
        context?.setLineCap(.round) 

        for stroke in strokes {
            context?.beginPath()

            context?.move(to: stroke.startPoint)
            context?.addLine(to: stroke.endPoint)

            context?.setStrokeColor(stroke.strokeColor)
            context?.strokePath()
        }

    }


    func erase() {
        strokes = []
        strokeColor = UIColor.black.cgColor
        setNeedsDisplay() // ditampilkan ke layar
    }



}

之后，将自定义视图指定给ViewController：

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var drawView: DrawView!


    override func viewDidLoad() {
        super.viewDidLoad()

    }



    @IBAction func yellowDidPressed(_ sender: Any) {
        drawView.strokeColor = UIColor.yellow.cgColor
    }


    @IBAction func redDidPressed(_ sender: Any) {
         drawView.strokeColor = UIColor.red.cgColor
    }

    @IBAction func blueDidPressed(_ sender: Any) {
         drawView.strokeColor = UIColor.blue.cgColor
    }

    @IBAction func erasedDidPressed(_ sender: Any) {
        drawView.erase()
    }

}

---

那么，如果我想在UIImageView上应用该自定义视图并将结果保存为新的UIImage，该怎么办呢？我是编程新手，实际上，我真的需要你的帮助。谢谢：）

同样的问题，有什么解决办法吗？

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var drawView: DrawView!


    override func viewDidLoad() {
        super.viewDidLoad()

    }



    @IBAction func yellowDidPressed(_ sender: Any) {
        drawView.strokeColor = UIColor.yellow.cgColor
    }


    @IBAction func redDidPressed(_ sender: Any) {
         drawView.strokeColor = UIColor.red.cgColor
    }

    @IBAction func blueDidPressed(_ sender: Any) {
         drawView.strokeColor = UIColor.blue.cgColor
    }

    @IBAction func erasedDidPressed(_ sender: Any) {
        drawView.erase()
    }

}