Yo dawg, I heard you like Blocks

gistfile1.m

// Loads the full-sized image ... might be big.
- (void)originalImageWithCompletionHandler:(DownloadedImageCompletionHandler)completionHandler {
	
	// First check to see if this image is cached in memory, if execute the handler passing in the image.
	if (nil != _originalImage) {
		if (completionHandler) {
			completionHandler(self, _photo, _photo.urlOriginal, _originalImage);
			
		}
		
		return;
	}
	
	
	// then check to see if this image already exists on disk, in which case, it should be loaded and the completion handler should be invoked.
	NSString *photoPath = [self storagePathForImageSize:ICDownloadedImageSizeOriginal];
	NSData *photoData = [NSData dataWithContentsOfFile:photoPath];
	
	
	// if photoData *isn't* nil, that means the file existed on disk (ie. had alread been loaded), and we can now execute the completion handler
	if (nil != photoData) {
		self.originalImage = [UIImage imageWithData:photoData]; // So we have this image cached in disk, we retain it
		if (completionHandler) {
			completionHandler(self, _photo, _photo.urlOriginal, _originalImage);
		}
		
		return;
	}
	
	
	// At this stage, the image wasn't in memory, and the image wasn't cached to disk, either, so it needs to be downloaded
	__block __typeof__(self) unretainedSelf = self;
	_connection = [[HTTPConnection alloc] initWithURLString:_photo.urlOriginal userInfo:nil completionHandler:^(HTTPConnection *connection, NSError *error, NSString *urlString, NSDictionary *userInfo, NSData *data) {
		if (nil != error) {
			NSLog(@"Error loading full sized image: %@", [error userInfo]);
			
			// Execute the DownloadedImageCompletionHandler, passing nil in for the image.
			if (completionHandler) {
				completionHandler(unretainedSelf, _photo, _photo.urlOriginal, nil);
			}
			
			return;
			
		}
		
		// No error with the connection, we have the data back, let's save the data to disk for future reference,
		// Then create an image with that, and execute the above completion handler with that data.
		
		// We can access the same photoPath from above (sneaky blocks are sneaky....)
		NSError *saveError = nil;
		if (![data writeToFile:photoPath options:NSDataWritingAtomic error:&saveError]) {
			NSLog(@"There was an error writing the downloaded image file to disk. The error: %@", [error userInfo]);
			
			// Execute the completion handler passing nil for the image, to indicate failure
			if (completionHandler) {
				completionHandler(unretainedSelf, _photo, _photo.urlOriginal, nil);
			}
			
			return;
		}
		
		
		// If the data was successfully written to disk, this means all is good.
		// We can now create a UIImage and execute the completion handler with that.
		unretainedSelf.originalImage = [UIImage imageWithData:data];
		
		if (completionHandler) {
			completionHandler(unretainedSelf, _photo, _photo.urlOriginal, unretainedSelf.originalImage);
		}
		
	}];
	
	
}