How is the relation between UIView's clipsToBounds and CALayer's masksToBounds?
A UIView
has a CALayer
. That's pretty sure. But both seem to provide something that means the same thing.
If I'd set clipsToBounds=YES
, would this also set the layer's masksToBounds=YES
? Why different names? Anyone knows?
They are different names because UIView
and CALayer
are different and have different terminology associated with them, but they are functionally equivalent. If you disassemble clipsToBounds
you will see it just calls masksToBounds
(disassembly from the simulator framework, so x86):
-(BOOL)[UIView(Rendering) clipsToBounds]
+0 3091938a 55 pushl %ebp
+1 3091938b 89e5 movl %esp,%ebp
+3 3091938d e800000000 calll 0x30919392
+8 30919392 59 popl %ecx
+9 30919393 8b4508 movl 0x08(%ebp),%eax
+12 30919396 8b5004 movl 0x04(%eax),%edx (CALayer)_layer
+15 30919399 8b8186cb1301 movl 0x0113cb86(%ecx),%eax masksToBounds
+21 3091939f 89450c movl %eax,0x0c(%ebp)
+24 309193a2 895508 movl %edx,0x08(%ebp)
+27 309193a5 c9 leave
+28 309193a6 e92e211801 jmpl 0x31a9b4d9
Some one asked what will happen if clipToBounds is set to false and maskToBounds is set to true or it can be better if someone add screenshots
I stumbled upon the same issue where I wanted to set corner radius and shadow both to the view.
but it is not possible because as soon as I set masksToBound to YES it removes the shadow but clip the content and if I set it to NO it shows the shadow but does not clip the content.
I have made the project which explains it better Understanding the ClipToBound And MasksToBound
I have come to the conclusion that CALayer is not a container but it is simply a class representing a rectangle on the screen with visual content. every drawing done on UIView goes on CALayer which causes the visual content to draw