How Do I Save What I have Drawn In A CGContext

UIImage *image = UIGraphicsGetImageFromCurrentImageContext(); 
NSData *imageData = UIImagePNGRepresentation(image);
[imageData writeToFile:@"image.png"];

CGImageRef imgRef = CGBitmapContextCreateImage(context);

UIImage* img = [UIImage imageWithCGImage:imgRef];

CGImageRelease(imgRef);