Rotate CGImage 90 degree clock wise

CGImage Rotation.png

CGImage_Rotation_Details.png

cgImageRotation.m

-(void) rotate90Degree:(CGImageRef) cgImageRef 
{
    int cgImageWidth = (int)CGImageGetWidth(cgImageRef);
    int cgImageHeight = (int)CGImageGetHeight(cgImageRef);
    
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    NSUInteger bytesPerPixel = 4;
    
    int targetWidth = cgImageHeight;
    int targetHeight = cgImageWidth;
    
    NSUInteger bytesPerRow = bytesPerPixel * targetWidth;
    NSUInteger bitsPerComponent = 8;

    CGContextRef context = CGBitmapContextCreate(nil, targetWidth, targetHeight,
                                                 bitsPerComponent, bytesPerRow, colorSpace,
                                                 kCGImageAlphaPremultipliedLast | kCGBitmapByteOrderDefault);
                                                 
    CGContextRotateCTM (context, -M_PI_2);
    CGContextTranslateCTM(context, -(int)targetHeight, 0);      
    
    CGContextDrawImage(context, CGRectMake(0, 0, cgImageWidth, cgImageHeight), cgImageRef);
}