UIImage from CGImageRef

Question

I am trying a simple test for a much more complex project but I am baffled as to why the code below is crashing and giving an EXC_BAD_ACCESS error? This is called from a UIView. ``` - (void)testing { NSString *imagePath = [[NSBundle mainBundle] pathForResource:@"ball.png" ofType:nil]; CGImageRef imageRef = [[[UIImage alloc]initWithContentsOfFile:imagePath]CGImage]; // CGImageRetain(imageRef); UIImage *newImage = [[UIImage alloc]initWithCGImage:imageRef]; UIImageView *iv = [[UIImageView alloc]initWithImage:newImage]; [self addSubview:iv]; } ``` My guess is that the CGImageRef is not being retained but adding CGImageRetain(imageRef); makes no difference. I should also note that this project has ARC turned on. EDIT I did a little bit more testing and have discovered that this is directly related to ARC as I created 2 basic projects including only the code above. The first with ARC turned off and it worked perfectly. The next with ARC turned on and BAM crash with the same error. The inter…

Accepted Answer

This line is the problem:

```
CGImageRef imageRef = [[[UIImage alloc]initWithContentsOfFile:imagePath]CGImage];
```

The created `UIImage` will be released immediately following this full-expression (e.g. after this line). So even trying to add a `CGImageRetain()` afterwards won't work.

The fundamental problem is the `CGImageRef` returned from `CGImage` is almost certainly an ivar of the `UIImage` and will be released when the `UIImage` is deallocted.

The generic way to fix this is to extend the lifetime of the `UIImage`. You can do this by placing the `UIImage` into a local variable and referencing it after your last reference to the `CGImage` (e.g. with `(void)uiimageVar`). Alternatively, you can retain the `CGImageRef` on that same line, as in

```
CGImageRef imageRef = CGImageRetain([[[UIImage alloc] initWithContentsOfFile:imagePath] CGImage]);
```

But if you do this, don't forget to release the `imageRef` when you're done.

UIImage from CGImageRef

Solution

Problem