Question

I am getting errors of type EXC-BAD-ACCESS where I create a new UIImage instance by assigning the value of a pre-existing UIImage (as below) and I am trying to figure out what the problem is. There is a heap of code to sort through and I am not sure where to start so I won’t bother posting source — but it might help me in my investigation of any of you could tell me What exactly is going on (memory-wise) when I create a new UIImage by assigning from another?

(in the .h)

UIImage* myExistsImage;

...

@property (retain) UIImage* myExistsImage;

...

-(UIImage*)rotateImage:(UIImage*)imageToRotate;



----------------------------------------------------


(in the .m)
@synthesize myExistsImage;

...

UIImage* myNewImage = [self rotateImage:myExistsImage];


...

-(UIImage*)rotateImage:(UIImage*)imageToRotate
{

UIImage* rotatedImage = imageToRotate;

//Rotate Image Here (details omitted)...

 return rotatedImage;
}

Answer 1

UIImage* rotatedImage = imageToRotate;

In that line, you’re not creating a new UIImage object; you’re simply creating a new pointer to the old one. If Rotate Image Here implies in-place modifications to rotatedImage, then you’re actually modifying myExistsImage as well.

If you want to create a new UIImage object to hold the rotated object, you’ll need to explicitly do so with the UIImage alloc and init methods.