Potential leak of object stored in context - ios

Question

I am getting a memory leak for this code.
- (CGContextRef) createARGBBitmapContextFromImage:(CGImageRef) imageRef {
CGContextRef context = NULL;
CGColorSpaceRef colorSpace;
void * bitmapData;
int bitmapByteCount;
int bitmapBytesPerRow;
// Get image width, height. We'll use the entire image.
size_t pixelsWide = CGImageGetWidth(imageRef);
size_t pixelsHigh = CGImageGetHeight(imageRef);
// Declare the number of bytes per row. Each pixel in the bitmap in this
// example is represented by 4 bytes; 8 bits each of red, green, blue, and
// alpha.
bitmapBytesPerRow = (pixelsWide * 4);
bitmapByteCount = (bitmapBytesPerRow * pixelsHigh);
// Use the generic RGB color space.
colorSpace = CGColorSpaceCreateDeviceRGB();
if (colorSpace == NULL)
{
fprintf(stderr, "Error allocating color space\n");
return NULL;
}
// Allocate memory for image data. This is the destination in memory
// where any drawing to the bitmap context will be rendered.
bitmapData = malloc( bitmapByteCount );
if (bitmapData == NULL)
{
fprintf (stderr, "Memory not allocated!");
CGColorSpaceRelease( colorSpace );
return NULL;
}
// Create the bitmap context. We want pre-multiplied ARGB, 8-bits
// per component. Regardless of what the source image format is
// (CMYK, Grayscale, and so on) it will be converted over to the format
// specified here by CGBitmapContextCreate.
context = CGBitmapContextCreate (bitmapData,
pixelsWide,
pixelsHigh,
8, // bits per component
bitmapBytesPerRow,
colorSpace,
kCGImageAlphaPremultipliedFirst);
if (context == NULL)
{
free (bitmapData);
fprintf (stderr, "Context not created!");
}
CGRect rect = {{0,0},{pixelsWide, pixelsHigh}};
//
// // Draw the image to the bitmap context. Once we draw, the memory
// // allocated for the context for rendering will then contain the
// // raw image data in the specified color space.
CGContextDrawImage(context, rect, self.CGImage);
// Make sure and release colorspace before returning
CGColorSpaceRelease( colorSpace );
return context;
}
error: Potential leak of object stored in context.

Answer 1

The memory leak analyser uses the name of the method to determine the change in retain count of the returned object. For Obj-C methods it is documented in Basic Memory Management Rules. It states
You create an object using a method whose name begins with “alloc”, “new”, “copy”, or “mutableCopy” (for example, alloc, newObject, or mutableCopy).
The name createARGBBitmapContextFromImage: is not matched by that rule. Instead you should name the method newARGBBitmapContextFromImage:.
Adding the word Create into a function name is used for C functions.