import UIKit
class DrawingView: UIView {
private var lines: [[CGPoint]] = []
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
guard let point = touches.first?.location(in: self) else { return }
lines.append([point])
setNeedsDisplay()
}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
guard let point = touches.first?.location(in: self), !lines.isEmpty else { return }
lines[lines.count - 1].append(point)
setNeedsDisplay()
}
override func draw(_ rect: CGRect) {
guard let context = UIGraphicsGetCurrentContext() else { return }
context.setStrokeColor(UIColor.black.cgColor)
context.setLineWidth(2)
context.setLineCap(.round)
for line in lines {
guard let firstPoint = line.first else { continue }
context.beginPath()
context.move(to: firstPoint)
for point in line.dropFirst() {
context.addLine(to: point)
}
context.strokePath()
}
}
func clear() {
lines.removeAll()
setNeedsDisplay()
}
}
class DrawingViewController: UIViewController {
let drawingView = DrawingView()
let clearButton = UIButton(type: .system)
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = .white
drawingView.frame = view.bounds
drawingView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
view.addSubview(drawingView)
clearButton.setTitle("Clear", for: .normal)
clearButton.frame = CGRect(x: 20, y: view.bounds.height - 60, width: 100, height: 40)
clearButton.autoresizingMask = [.flexibleTopMargin, .flexibleRightMargin]
view.addSubview(clearButton)
clearButton.addTarget(self, action: #selector(clearDrawing), for: .touchUpInside)
}
@objc func clearDrawing() {
drawingView.clear()
}
}We created a DrawingView subclass of UIView to handle touch events and drawing. It keeps an array of lines, where each line is an array of points. When the user touches the screen, a new line starts. As the finger moves, points are added to the current line. The draw(_:) method draws all lines with smooth black strokes.
The clear() method empties all lines and refreshes the view.
The DrawingViewController sets up the drawing view and a clear button. The button calls clear() on the drawing view to erase the canvas.
This approach uses UIKit touch handling and Core Graphics drawing to create a simple finger drawing canvas.
