代码截屏

   UIGraphicsBeginImageContext(view.frame.size);

对哪个视图截图给定大小的图片

   [ view.layer renderInContext:UIGraphicsGetCurrentContext()];

获取截图的图片对象

   UIImage * p_w_picpath = UIGraphicsGetImageFromCurrentImageContext();

结束绘制图片

    UIGraphicsEndImageContext();

保存到相册

   UIImageWriteToSavedPhotosAlbum(p_w_picpath, nil, nil, nil);