UIView如何绘制相机选择器

Question

我正在寻找在视图周围绘制此类框架的方法。是否可以使用 iOS 原生绘图？

Answer 1

使用本机渲染可以很容易地绘制它。一种方法是创建一个新视图并覆盖 draw rect 方法。您可以执行以下操作：

class ViewWithFrame: UIView {

    var color: UIColor = UIColor.black { didSet { setNeedsDisplay() } }
    var lineThickness: CGFloat = 5 { didSet { setNeedsDisplay() } }
    var lineLength: CGFloat = 30.0 { didSet { setNeedsDisplay() } }

    override var frame: CGRect { didSet { setNeedsDisplay() } }
    override func layoutSubviews() {
        super.layoutSubviews()
        setNeedsDisplay()
    }

    override func draw(_ rect: CGRect) {
        super.draw(rect)

        var paths: [UIBezierPath] = [UIBezierPath]()

        // Top left
        paths.append({
            let path = UIBezierPath()
            path.move(to: .zero)
            path.addLine(to: CGPoint(x: lineLength, y: 0.0))
            path.addQuadCurve(to: CGPoint(x: lineLength-lineThickness, y: lineThickness), controlPoint: CGPoint(x: lineLength, y: lineThickness))
            path.addLine(to: CGPoint(x: lineThickness, y: lineThickness))
            path.addLine(to: CGPoint(x: lineThickness, y: lineLength-lineThickness))
            path.addQuadCurve(to: CGPoint(x: 0.0, y: lineLength), controlPoint: CGPoint(x: lineThickness, y: lineLength))
            path.close()
            return path
            }())

        // Top right
        paths.append({
            let path = UIBezierPath()
            path.move(to: CGPoint(x: frame.width, y: 0.0))
            path.addLine(to: CGPoint(x: frame.width-lineLength, y: 0.0))
            path.addQuadCurve(to: CGPoint(x: frame.width-(lineLength-lineThickness), y: lineThickness), controlPoint: CGPoint(x: frame.width-lineLength, y: lineThickness))
            path.addLine(to: CGPoint(x: frame.width-lineThickness, y: lineThickness))
            path.addLine(to: CGPoint(x: frame.width-lineThickness, y: lineLength-lineThickness))
            path.addQuadCurve(to: CGPoint(x: frame.width, y: lineLength), controlPoint: CGPoint(x: frame.width-lineThickness, y: lineLength))
            path.close()
            return path
            }())

        // TODO: add 2 bottom paths

        color.setFill()
        paths.forEach { [=10=].fill() }
    }

}

底部部分仍然需要绘制，但我希望你知道如何绘制。

记下对 setNeedsDisplay 的所有调用。这就是将在下一个运行循环中触发 draw rect 方法的方法，它应该针对可能影响绘图的每个视图更改执行此操作，其中还包括视图大小。

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