이미지뷰를 캡쳐하기

UIGraphicsBeginImageContext(cardView.frame.size);

[cardView.layer renderInContext:UIGraphicsGetCurrentContext()];

screenShot = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

NSString *imagePath = [model imagePath];

[UIImagePNGRepresentation(screenShot) writeToFile:imagePath atomically:YES];