Why masksToBounds = YES prevents CALayer shadow?

Question

With the following snippet, I\'m adding a drop shadow effect to one my UIView. Which works pretty well. But as soon as I set the view\'s masksToBounds prope

Answer 1

It's iOS 6 now, things might have changed. TheSquad's answer don't work for me until I managed to add one more line view2.layer.masksToBounds = NO;, otherwise shadow doesn't show. Although documentation says masksToBounds is NO by default, my code shows the opposite.

Here is how I make a rounded corner button with shadow, which is among the most commonly used code snippet in my app.

button.layer.masksToBounds = YES;
button.layer.cornerRadius = 10.0f;

view.layer.masksToBounds = NO;      // critical to add this line
view.layer.cornerRadius = 10.0f;
view.layer.shadowOpacity = 1.0f;
// set shadow path to prevent horrible performance
view.layer.shadowPath = 
    [UIBezierPath bezierPathWithRoundedRect:_button.bounds cornerRadius:10.0f].CGPath;      

[view addSubview:button];

EDIT

If views need to be animated or scrolled, masksToBounds = YES tax performance significantly, which means animation will probably get stuttered. To get rounded corner and shadow AND smooth animation or scrolling, use following code instead:

button.backgroundColor = [UIColor clearColor];
button.layer.backgroundColor = [UIColor redColor].CGColor;
button.layer.masksToBounds = NO;
button.layer.cornerRadius = 10.0f;

view.layer.shadowOpacity = 0.5f;
view.layer.shadowPath = [UIBezierPath bezierPathWithRoundedRect:_button.bounds cornerRadius:10.0f].CGPath;
view.layer.shadowOffset = CGSizeMake(0.0f, 4.0f);
view.layer.shadowRadius = 2.0f;
view.layer.masksToBounds = NO;
view.layer.cornerRadius = 10.0f;  

[view addSubview:button];