Функция поворота CGImage

Материал взят из http://connordenman.wordpress.com/2010/09/18/rotation-of-cgimage-iphoneipad-improved/

- (CGImageRef)CGImageRotatedByAngle:(CGImageRef)imgRef angle:(CGFloat)angle
{
CGFloat angleInRadians = angle * (M_PI / 180);
CGFloat width = CGImageGetWidth(imgRef);
CGFloat height = CGImageGetHeight(imgRef);

CGRect imgRect = CGRectMake(0, 0, width, height);
CGAffineTransform transform = CGAffineTransformMakeRotation(angleInRadians);
CGRect rotatedRect = CGRectApplyAffineTransform(imgRect, transform);

CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef bmContext = CGBitmapContextCreate(NULL,
rotatedRect.size.width,
rotatedRect.size.height,
8,
0,
colorSpace,
kCGImageAlphaPremultipliedFirst);
CGContextSetAllowsAntialiasing(bmContext, YES);
CGContextSetInterpolationQuality(bmContext, kCGInterpolationHigh);
CGColorSpaceRelease(colorSpace);
CGContextTranslateCTM(bmContext,
+(rotatedRect.size.width/2),
+(rotatedRect.size.height/2));
CGContextRotateCTM(bmContext, angleInRadians);
CGContextDrawImage(bmContext, CGRectMake(-width/2, -height/2, width, height),
imgRef);

CGImageRef rotatedImage = CGBitmapContextCreateImage(bmContext);
CFRelease(bmContext);
[(id)rotatedImage autorelease];

return rotatedImage;
}