Memory problems while reading iphone camera roll with AlAssetsLibrary

Question

I'm trying to get last picture from iphone camera roll. I use the following code:

UIImage* __block image = [[UIImage alloc] init];
ALAssetsLibrary* library = [[ALAssetsLibrary alloc] init];

[library enumerateGroupsWithTypes:ALAssetsGroupSavedPhotos usingBlock:^(ALAssetsGroup* group, BOOL* stop) {

    [group setAssetsFilter:[ALAssetsFilter allPhotos]];

    if ([group numberOfAssets] > 0) {
        [group enumerateAssetsAtIndexes:[NSIndexSet indexSetWithIndex:[group numberOfAssets]-1] options:NSEnumerationConcurrent usingBlock:^(ALAsset* alAsset, NSUInteger index, BOOL* innerStop) {
            if (alAsset) {
                ALAssetRepresentation* rawImage = [alAsset defaultRepresentation];
                image = [UIImage imageWithCGImage:[rawImage fullScreenImage]];
                [self doTheJobWithImage:image];
                // Inside doTheJobWithImage: a segue is also performed at the end
            }
        }];
    }
} failureBlock:^(NSError* error) {
    NSLog(@"Error: %@", [error localizedDescription]);
}];

It works but with flaws (I'm using Instruments and Zombies to debug it):

It seems to read every picture inside camera roll. So, first question: doesn't enumerateAssetsAtIndexes: only retrieve the specified images (atIndexes)? What's wrong with my code?
Adding to previous problem, memory becomes a problem when a lot of pictures are in camera roll. My app crashes if too many or, if it works, it seems retrieved images are NEVER deallocated, so the second or third time i call this code, it crashes anyway due to memory leaks. So second question: how do I force my code to deallocate everything after calling doTheJobWithImage: ?

I'm using xcode 4.6, ios 6 and ARC. Thanks in advance.

score 1 · Answer 1 · answered Feb 17 '13 at 21:35

After few hours, I figured out that nothing is wrong with the code here. It is the right code to extract last picture in camera roll (if somebody ever needs it). The problem was inside doTheJobWithImage: , I solved it replacing

[self doTheJobWithImage:image];

and storing the resulting image somewhere else, and THEN performing doTheJobWithImage: after picture enumeration was done.. Saying this just in case somebody else is interested.

Memory problems while reading iphone camera roll with AlAssetsLibrary

1 Answers1