UIImage + rendering blocks

UIImage+render.m

#import <UIKit/UIKit.h>
#import <QuartzCore/QuartzCore.h>

typedef void(^UIImageRenderBlock)(CGContextRef context);

@interface UIImage (render)

+(UIImage *)imageWithSize:(CGSize) canvasSize block:(UIImageRenderBlock) aBlock;

@end

@implementation UIImage (render)

+(UIImage *)imageWithSize:(CGSize) canvasSize block:(UIImageRenderBlock) aBlock {
  
	CGContextRef		context;
	void				*bitmapData;
	CGColorSpaceRef		colorSpace;
	int					bitmapByteCount;
	int					bitmapBytesPerRow;
  CGImageRef  resultImage;
  UIImage     *image;
  
	//
	bitmapBytesPerRow	= canvasSize.width * 4;
	bitmapByteCount		= (bitmapBytesPerRow * canvasSize.height);
	
	//Create the color space
	colorSpace = CGColorSpaceCreateDeviceRGB();
	
	bitmapData = malloc( bitmapByteCount );
	
	//Check the the buffer is alloc'd
	if( bitmapData == NULL ){
		NSLog(@"Buffer could not be alloc'd");
	}
	
	//Create the context
	context = CGBitmapContextCreate(bitmapData, canvasSize.width, canvasSize.height, 8, bitmapBytesPerRow, colorSpace, kCGImageAlphaPremultipliedLast);
	
	if( context == NULL ){
		NSLog(@"Context could not be created");
	}
	
	//Render user data
  aBlock(context);
	
	//The contents of the context could be saved out as follows
	//Get the result image
  resultImage = CGBitmapContextCreateImage(context);

  //Save the image
  image =  [UIImage imageWithCGImage:resultImage];

	//Cleanup
  CGImageRelease(resultImage);
	free(bitmapData);
	CGColorSpaceRelease(colorSpace);
  
  return image;
    
}

@end