CAShapeLayer mask view

Question

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.

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];

}

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;

}

it don't show anything.

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

Answer 1

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;
}