Transform an image threadsafe

UIImage+Transform.h

//
//  UIImage+Transform.h
//  TestImage
//
//  Created by Robert Saunders on 04/10/2012.
//  Copyright (c) 2012 Robert Saunders. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface UIImage (Transform)

// Thread-safe
- (UIImage*) imageByApplyingTransfromAboutCenter:(CGAffineTransform)transform;

@end

UIImage+Transform.m

//
//  UIImage+Transform.m
//  TestImage
//
//  Created by Robert Saunders on 04/10/2012.
//  Copyright (c) 2012 Robert Saunders. All rights reserved.
//

#import "UIImage+Transform.h"

@implementation UIImage (Transform)




- (UIImage*) imageByApplyingTransfromAboutCenter:(CGAffineTransform)transform
{
    CGFloat imageWidth = self.size.width;
    CGFloat imageHeight = self.size.height;
    
    CGImageRef imageRef = [self CGImage];
    CGBitmapInfo bitmapInfo = CGImageGetBitmapInfo(imageRef);
    CGColorSpaceRef colorSpaceInfo = CGColorSpaceCreateDeviceRGB();

    bitmapInfo = kCGImageAlphaNone;
    
    CGContextRef bitmap =
    CGBitmapContextCreate(NULL,
                          imageWidth ,
                          imageHeight,
                          8,
                          (4 * self.size.width),
                          colorSpaceInfo,
                          kCGImageAlphaPremultipliedFirst);
    
    CGContextTranslateCTM(bitmap, imageWidth / 2 , imageHeight / 2);
    CGContextConcatCTM (bitmap, transform);
    
    CGRect rectForDrawing = CGRectMake(-imageWidth / 2 , -imageHeight / 2, imageWidth, imageHeight);
    
    CGContextDrawImage(bitmap, rectForDrawing, imageRef);
    
    CGImageRef ref = CGBitmapContextCreateImage(bitmap);
    UIImage* newImage = [UIImage imageWithCGImage:ref];
    
    CGContextRelease(bitmap);
    CGImageRelease(ref);
    
    return newImage;
}

@end