Scale UIImage

gistfile1.m

- (UIImage *)withNewSize:(CGSize)newSize
{
    CGRect newRect = CGRectIntegral(CGRectMake(0.0f, 0.0f, newSize.width, newSize.height));
    CGImageRef imageRef = self.CGImage;
    
    UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0f);
    CGContextRef context = UIGraphicsGetCurrentContext();
    
    CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
    CGAffineTransform flipVertical = CGAffineTransformMake(1, 0, 0, -1, 0, newSize.height);
    CGContextConcatCTM(context, flipVertical);
    CGContextDrawImage(context, newRect, imageRef);
    CGImageRef newImageRef = CGBitmapContextCreateImage(context);
    UIImage *newImage = [UIImage imageWithCGImage:newImageRef];
    CGImageRelease(newImageRef);
    UIGraphicsEndImageContext();
    
    return newImage;
}