iOS Memory leak in UIImage

Question

I'm using ios 7 and I need to do:

In separete thread I want to create image from network and put it into UIImageView. I need to do this every 200 ms.

My code looks like:

- (void)startPreview:(CGFloat)specialFramesRates;
{
    if(isPreview)
        return;

    [Utils runOnThread:^{
        [Log log:@"Start preview"];   //here we have a leak

        isPreview = YES;
        while(isPreview) {
            [self getNewBitmap];

            sleep(fpsTime);

            if(!isPreview)
                break;

            if(checkAvabilityCam > 10)
                break;
        }

        [Log log:@"Stoped preview"];
    }];
}

- (void)getNewBitmap
{   
    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:url];
    [request setTimeoutInterval:1];
    [request setHTTPMethod:@"GET"];

    NSError *requestError;
    NSURLResponse *urlResponse = nil;


    NSData *response = [NSURLConnection sendSynchronousRequest:request returningResponse:&urlResponse error:&requestError];
    [UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
    if(delegate && response) {
        checkAvabilityCam = 0;

        //TODO what I should do here?
        UIImage *image = [UIImage imageWithData:newImage];  //HERE IS LEAK !!!!

        [delegate onShowImage:response];  //here I show image in main thread
        image = nil;   //With or without doesn't work
        return;
    }

    checkAvabilityCam++;
    if(delegate)
        [delegate onShowDefaultImage];
}

In this line of code I have a problem:

//TODO what I should do here?
UIImage *image = [UIImage imageWithData:newImage];  //HERE IS LEAK !!!!

[delegate onShowImage:response];  //here I show image in main thread
image = nil;   //With or without doesn't work

What can I use instead of "[UIImage imageWithData:]" ? I tried save into file and load but with the same effect. What should I do?

Answer 1

UIImage *image = [UIImage imageWithData:newImage];  //HERE IS LEAK !!!!

You are creating an autoreleased object here. Since you're doing this on a background thread, any autoreleased objects you create won't get released unless your thread has its own autorelease pool.

If you are using ARC, create an autorelease pool with the @autoreleasepool keyword:

@autoreleasepool {
    UIImage *image = [UIImage imageWithData:newImage];

    // Do stuff with image
}

If you're not using ARC, create an autorelease pool manually:

NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
UIImage *image = [UIImage imageWithData:newImage];

// Do stuff with image

[pool release];