ios7 实现应用内保真截屏

    CGSize size = self.content.bounds.size;
    
    UIGraphicsBeginImageContextWithOptions(size, NO, [UIScreen mainScreen].scale);
    
    [self.content drawViewHierarchyInRect:self.content.bounds afterScreenUpdates:YES];
    
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();