- (void)savePicToPhotoes

{

    UIGraphicsBeginImageContext(self.view.bounds.size);

    CGContextRef ref = UIGraphicsGetCurrentContext();

    [_board.layer renderInContext:ref];

    UIImage *img = UIGraphicsGetImageFromCurrentImageContext();

    UIImageWriteToSavedPhotosAlbum(img, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);

}

#pragma mark 显示提示框

- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo{

    //创建alert

    UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"图片已保存到相册" message:nil preferredStyle:UIAlertControllerStyleAlert];

    //创建action

    UIAlertAction *action = [UIAlertAction actionWithTitle:@"确定" style:UIAlertActionStyleDefault handler:nil];

    [alert addAction:action];

    [self presentViewController:alert animated:YES completion:nil];

}