Subview appears underneath superviews layer.border?

iphone ios cocoa-touch uiview calayer
Ser Pounce picture Ser Pounce · Mar 19, 2013 · Viewed 9k times · Source

I have a UIView in which I define it's border in the following manner:

self.layer.borderColor = [UIColor blackColor].CGColor;
self.layer.borderWidth = 3;

I attach a subview to this UIView, and when I move the subview over the border, it goes underneath it. Is this the intended behavior? Is there anyway to make the subview go on top of it?

Answer

Guo Luchuan picture Guo Luchuan · Mar 19, 2013

According to the Apple specification: It is composited above the receiver’s contents and sublayers.

So, the border will always be above of all your subviews, even if you bring your subview to the front and so on.

So I make a background view to fake the border.

E.g.:

UIView *backgroundView = [[UIView alloc] initWithFrame:CGRectMake(100, 100, 200, 200)];
backgroundView.backgroundColor = [UIColor blackColor];
backgroundView.clipsToBounds = NO;

UIView *bView = [[UIView alloc] initWithFrame:CGRectInset(backgroundView.bounds, 3, 3)];
bView.backgroundColor = [UIColor redColor];

UIView *cView = [[UIView alloc] initWithFrame:CGRectMake(-50, -50, 100, 100)];
cView.backgroundColor = [UIColor yellowColor];
[bView addSubview:cView];

[backgroundView addSubview:bView];

[self.window addSubview:backgroundView];

and the effect:

enter image description here

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