Swift检测绘图中发生触摸的位置：

import UIKit

class DrawingView: UIView {
    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        if let touch = touches.first {
            let location = touch.location(in: self)
            print("触摸开始位置：\(location)")
        }
    }
    
    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
        if let touch = touches.first {
            let location = touch.location(in: self)
            print("触摸移动位置：\(location)")
        }
    }
    
    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
        if let touch = touches.first {
            let location = touch.location(in: self)
            print("触摸结束位置：\(location)")
        }
    }
    
    override func touchesCancelled(_ touches: Set<UITouch>, with event: UIEvent?) {
        // 触摸取消处理
    }
}

// 在视图控制器中使用DrawingView
class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let drawingView = DrawingView(frame: CGRect(x: 0, y: 0, width: 200, height: 200))
        drawingView.backgroundColor = .white
        view.addSubview(drawingView)
    }
}