shrinkImage

gistfile1.m

static UIImage *shrinkImage(UIImage *original, CGSize size) {
    CGFloat scale = [UIScreen mainScreen].scale;
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    
    CGContextRef context = CGBitmapContextCreate(NULL, size.width * scale,
												 size.height * scale, 8, 0, colorSpace, kCGImageAlphaPremultipliedFirst);
    CGContextDrawImage(context,
					   CGRectMake(0, 0, size.width * scale, size.height * scale),
					   original.CGImage);
    CGImageRef shrunken = CGBitmapContextCreateImage(context);
    UIImage *final = [UIImage imageWithCGImage:shrunken];
    
    CGContextRelease(context);
    CGImageRelease(shrunken);	
	
    return final;
}