Memory leak when getting data out of UIImage - ios

Question

I want to extract data from UIImage and do something with that data.
I found an memory issue while extracting the data from the UIImage.
To isolate the issue i created a new project with just a method that extract data from UIImage.
-(void)runMemoryValidation:(NSArray*)images {
for ( int i=0; i<images.count; i++) {
#autoreleasepool {
NSString* imageName = [images objectAtIndex:i];
UIImage* image = [UIImage imageNamed:imageName];
NSUInteger width = 500;//CGImageGetWidth(image.CGImage);
NSUInteger height = 500;//CGImageGetHeight(image.CGImage);
//Ref<IntMatrix> matrix(new IntMatrix(width,height));
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
unsigned char *data = (unsigned char*) calloc(height * width * 4, sizeof(unsigned char));
NSUInteger bytesPerPixel = 4;
NSUInteger bytesPerRow = bytesPerPixel * width;
NSUInteger bitsPerComponent = 8;
CGContextRef context = CGBitmapContextCreate(data, width, height,
bitsPerComponent, bytesPerRow, colorSpace,
kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
CGColorSpaceRelease(colorSpace);
CGContextDrawImage(context, CGRectMake(0, 0, width, height), image.CGImage);
CGContextRelease(context);
free(data);
}
}
}
I'm sending this method 100 file names and for each loop i load the image and extract the data.
Attached a screenshot, you can see the memory getting higher very quickly and doesn't get released after the for loop finish
What am i doing wrong ?
Thanks!

Answer 1

You are not doing anything wrong related to memory management in this code. As #picciano said in his comment +imageNamed: method caches the images it loads, therefore use +imageWithContentsOfFile: method which doesn't. Also do your measures on an actual device, since there's a differece in memory usage, pressure, etc. when testing on the simulator.