Question

我有一个问题。我在网上寻找答案，我不明白为什么不工作。我必须做一些我无法弄明白的愚蠢错误。

如果我做：

- (void)viewDidLoad
{
    [super viewDidLoad];

    UIView * view = [[UIView alloc]initWithFrame:CGRectMake(10, 10, 300, 400)];
    view.backgroundColor = [UIColor blueColor];
    [self.view addSubview:view];

}

它会在屏幕上创建蓝色视图，但如果我创建

- (void)viewDidLoad
{
    [super viewDidLoad];

    UIView * view = [[UIView alloc]initWithFrame:CGRectMake(10, 10, 300, 400)];
    view.backgroundColor = [UIColor blueColor];
    [self.view addSubview:view];

    CAShapeLayer * layer = [[CAShapeLayer alloc]init];
    layer.frame = CGRectMake(10, 10, 30, 30);
    layer.fillColor = [[UIColor blackColor] CGColor];

    view.layer.mask = layer;

}

它没有显示任何内容。

如果我理解正确，应该掩饰（10,10,30,30）？

Answer 1

您需要在CAShapeLayer上设置路径：

- (void)viewDidLoad
{
    [super viewDidLoad];


    UIView * view = [[UIView alloc]initWithFrame:CGRectMake(10, 10, 300, 400)];
    view.backgroundColor = [UIColor blueColor];
    [self.view addSubview:view];

    CAShapeLayer * layer = [[CAShapeLayer alloc]init];
    layer.frame = view.bounds;
    layer.fillColor = [[UIColor blackColor] CGColor];

    layer.path = CGPathCreateWithRect(CGRectMake(10, 10, 30, 30), NULL);

    view.layer.mask = layer;
}

Answer 2

谢谢你的回答，cncool。

如果有人在几个小时内无法在SO上找到合适的答案，就像我刚才那样，我已经在Swift 2.2中为masking / clipping {{1 } UIView / CGRect：

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

UIBezierPath

用法：

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

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

        maskLayer.path = path.CGPath

        self.layer.mask = maskLayer
    }
}

希望将来能节省一些时间：）

CAShapeLayer面具视图

2 个答案: