CAShapeLayer面具视图 [英] CAShapeLayer mask view

问题描述

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清楚的愚蠢错误。

I have one problem. I look for the answers on the net and I don't understand why is not working. I must do some stupid mistake which I can't figure it out.

如果我做的话：

- (void)viewDidLoad
{
    [super viewDidLoad];

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

}

它在屏幕上创建蓝色视图，但如果我制作

it create blue view on the screen, but if I make

- (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。

it don't show anything.

如果我理解正确，它应该掩盖（10,10,30,30）？

If I understand correctly it should mask at (10,10,30,30)?

推荐答案

您需要在CAShapeLayer上设置路径：

You need to set the path on the CAShapeLayer:

- (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;
}

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