问题
I am using multiple CALayer's in my application with large UIImage as contents. unfortunately, when I don't need the layer nor the image - the memory is not freed.
the code I use to create the layer is:
UIImage *im = [UIImage imageNamed:@"image_1.jpg"];
CALayer * l = [CALayer layer];
[l setBounds:CGRectMake(0, 0, 1024, 768)];
[l setPosition:CGPointMake(512, 384)];
[l setAnchorPoint:CGPointMake(0.5, 0.5)];
[l setHidden:NO];
[l setContents:(id) im.CGImage];
[self.layer addSublayer:l]; // self is a subclass of UIView
[self.tmpArr addObject:l]; // self.tmpArr contains the layers I am using (one in this example)
the code I use to release the layer and it's contents is :
CALayer * l = [self.tmpArr objectAtIndex:i];
[l removeFromSuperlayer];
[l setHidden:YES];
[l setContents:nil];
[self.tmpArr removeAllObjects];
when I'm using the instruments memory profiler I see the real memory increasing when creating the layer but never decreasing when freeing there. I can't use release since I am using ARC. what do I do wrong here ?
Thanks.
回答1:
UIImage's imageNamed: method uses a static cache that is only released upon tight memory situations.
Your options are:
- Use
-[UIImage imageWithContentsOfFile:]instead. - Ignore the problem. The cache is cleaned up when a memory notification comes in.
回答2:
Just for documenting another answer. The image that I created in my code was drawn at runtime using CGImageCreateWithImageInRect. The produced object is CGImageRef. I simply forgot to release it using CGImageRelease causing the memory consumption to increase gradually and after 3 or 4 animation, the application crashes due to memory constraint.
Always release an CGImageRef.
来源：https://stackoverflow.com/questions/10494980/cant-release-unused-calayer-memory-when-using-multiple-layers