问题
I want to set the contents of a CALayer to an image. The CALayer has a contents property The documentation on that property says that "a layer can set this property to a CGImageRef to display the image as its contents." But the property takes an id so in Xcode I get the following issue:
Semantic Issue: Incompatible pointer types assigning to 'id' from 'CGImageRef' (aka 'struct CGImage *')
How can I assign a CGImageRef to the contents property when it only takes an id? What am I missing here?
回答1:
Explicitly casting CGImageRef to id should fix the warning. For example,
CGImageRef imageRef;
...
layer.contents = (id) imageRef;
should be working fine.
回答2:
Instead of using (id) you can use (__bridge id) to solve the type convert issue.
来源：https://stackoverflow.com/questions/5455080/how-do-i-set-the-contents-of-a-calayer-to-a-cgimageref