只需用矩形掩盖UIView即可

Question

我想知道如何简单地掩盖任何类型的UIView的可见区域.到目前为止,我所阅读的所有答案/教程都描述了用图像,渐变或创建圆角来掩盖,这比我以前的方式更先进.

示例:我有一个带有边界(0,0,100,100)的UIView,我想用掩码切掉视图的右半部分.因此我的面具框架将是(0,0,50,100).

知道怎么做这个简单吗？我不想覆盖drawrect方法,因为这应该适用于任何UIView.

我试过这个,但它只是让整个视图看不见.

CGRect mask = CGRectMake(0, 0, 50, 100);
UIView *maskView = [[UIView alloc] initWithFrame:mask];
viewToMask.layer.mask = maskView.layer;

Answer 1

感谢MSK的链接,这是我使用的方式,效果很好:

// Create a mask layer and the frame to determine what will be visible in the view.
CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];
CGRect maskRect = CGRectMake(0, 0, 50, 100);

// Create a path with the rectangle in it.
CGPathRef path = CGPathCreateWithRect(maskRect, NULL);

// Set the path to the mask layer.
maskLayer.path = path;

// Release the path since it's not covered by ARC.
CGPathRelease(path);

// Set the mask of the view.
viewToMask.layer.mask = maskLayer;

Answer 2

谢谢你的回答.

如果有人几个小时都找不到适合这个问题的答案,就像我刚刚做的那样,我已经在Swift 2.2中组装了一个工作要点for masking/ clipping UIViewwith CGRect/ UIBezierPath:

https://gist.github.com/Flar49/7e977e81f1d2827f5fcd5c6c6a3c3d94

extension UIView {

    func mask(withRect rect: CGRect, inverse: Bool = false) {
        let path = UIBezierPath(rect: rect)
        let maskLayer = CAShapeLayer()

        if inverse {
            path.append(UIBezierPath(rect: self.bounds))
            maskLayer.fillRule = kCAFillRuleEvenOdd
        }

        maskLayer.path = path.cgPath

        self.layer.mask = maskLayer
    }

    func mask(withPath path: UIBezierPath, inverse: Bool = false) {
        let path = path
        let maskLayer = CAShapeLayer()

        if inverse {
            path.append(UIBezierPath(rect: self.bounds))
            maskLayer.fillRule = kCAFillRuleEvenOdd
        }

        maskLayer.path = path.cgPath

        self.layer.mask = maskLayer
    }
}

用法:

let viewSize = targetView.bounds.size
let rect = CGRect(x: 20, y: 20, width: viewSize.width - 20*2, height: viewSize.height - 20*2)

// Cuts rectangle inside view, leaving 20pt borders around
targetView.mask(withRect: rect, inverse: true)

// Cuts 20pt borders around the view, keeping part inside rect intact
targetView.mask(withRect: rect)

希望将来能节省一些时间:)

Answer 3

根本不需要任何面具.只需将其放入包含较小框架的包装视图中,然后设置clipsToBounds即可.

wrapper.clipsToBounds = YES;