Objectivec Facebook 的 UIActivityViewController 不显示默认文本

我使用的是UIActivityViewController，它提供了一些默认文本和链接.所有社交媒体(短信、邮箱、twitter)都会显示默认文本和URL.然而，当显示URL图像时，默认文本不会显示(只是空白).代码如下:

    NSString *shareStr = [NSString stringWithFormat:@""some text"];
    NSURL *website = [NSURL URLWithString:@"website"];
    NSArray *shareAray = @[shareStr,website];

    [self viewWillDisappear:YES];

    UIActivityViewController *activityController = [[UIActivityViewController alloc]initWithActivityItems:shareAray
                                                                                    applicationActivities:nil];

    if([activityController respondsToSelector:@selector(popoverPresentationController)] )
        activityController.popoverPresentationController.barButtonItem = self.shareButton;


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

    [activityController setCompletionHandler:^(NSString *activityType, BOOL completed){
        if (!activityType || UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad)
        {
            [self viewWillAppear:YES];
        }
    }];

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