I am trying to figure out why iOS crash my application in the harsh way (no crash logs, immediate shudown with black screen of death with spinner shown for a while). It happens when I render content for CALayer using Quartz. I suspected the memory issue (happens only when testing on the device), but memory logs, as well as instruments allocation logs looks quite OK. Let me past in the fatal function:

- (void)renderTiles{

    if (rendering) {
        //NSLog(@"====== RENDERING TILES SKIP =======");
        return;
    }
    rendering = YES;



    CGRect b = tileLayer.bounds;
    CGSize s = b.size;
    CGFloat imageScale = [[UIScreen mainScreen] scale];
    s.height *= imageScale;
    s.width *= imageScale;

    dispatch_async(queue, ^{

        NSLog(@"");
         NSLog(@"====== RENDERING TILES START =======");

        NSLog(@"1. Before creating context");
        report_memory();

        CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
        NSLog(@"2. After creating color space");
        report_memory();

        NSLog(@"3. About to create context with size: %@", NSStringFromCGSize(s));
        CGContextRef ctx = CGBitmapContextCreate(NULL, s.width, s.height, 8, 0, colorSpace, kCGImageAlphaPremultipliedLast);

        NSLog(@"4. After creating context");
        report_memory();

        CGAffineTransform flipTransform = CGAffineTransformMake(1.0, 0.0, 0.0, -1.0, 0.0, s.height);
        CGContextConcatCTM(ctx, flipTransform);

        CGRect tileRect = CGRectMake(0, 0, tileImageScaledSize.width, tileImageScaledSize.height);
        CGContextDrawTiledImage(ctx, tileRect, tileCGImageScaled);

        NSLog(@"5. Before creating cgimage from context");
        report_memory();

        CGImageRef cgImage = CGBitmapContextCreateImage(ctx);
        NSLog(@"6. After creating cgimage from context");
        report_memory();

        dispatch_sync(dispatch_get_main_queue(), ^{
            tileLayer.contents = (id)cgImage;        
        });

        NSLog(@"7. After asgning tile layer contents = cgimage");
        report_memory();

        CGColorSpaceRelease(colorSpace);
        CGContextRelease(ctx);
        CGImageRelease(cgImage);

        NSLog(@"8. After releasing image and context context");
        report_memory();


        NSLog(@"====== RENDERING TILES END =======");
        NSLog(@"");
        rendering = NO;

    });
}

Here are the logs:

====== RENDERING TILES START =======
1. Before creating context
    Memory in use (in bytes): 28340224 / 519442432 (5.5%)
2. After creating color space
    Memory in use (in bytes): 28340224 / 519442432 (5.5%)
3. About to create context with size: {6324, 5208}
4. After creating context
    Memory in use (in bytes): 28344320 / 651268096 (4.4%)
5. Before creating cgimage from context
    Memory in use (in bytes): 153649152 / 651333632 (23.6%)
6. After creating cgimage from context
    Memory in use (in bytes): 153649152 / 783159296 (19.6%)
7. After asgning tile layer contents = cgimage
    Memory in use (in bytes): 153653248 / 783253504 (19.6%)
8. After releasing image and context context
     Memory in use (in bytes): 21688320 / 651288576 (3.3%)
====== RENDERING TILES END =======

Application crashes in random places. Sometimes when reaching en of the function and sometime in random step.

Which direction should I look for a solution? Is is possible that GDC is causing the problem? Or maybe the context size or some Core Animation underlying references?