iOS 7 中的 UIActivityViewController

在我的应用程序中，我添加了这些代码行以合并 uiactivityviewcontroller 的功能

    UIImage *yourImage = someImg;
    UIActivityViewController *activityVC = [[UIActivityViewController alloc] initWithActivityItems:[NSArray arrayWithObjects:@"abcdefgh",yourImage, nil] applicationActivities:nil];
    activityVC.excludedActivityTypes = @[ UIActivityTypeMessage ,UIActivityTypeAssignToContact,UIActivityTypeSaveToCameraRoll];
    [self presentViewController:activityVC animated:YES completion:nil]; 

和 UIActivityViewContoller 工作正常，但 UI 是这样的：没有 FB 图标，没有 Twitter 图标，这是 iPad 的屏幕截图：

但在 iOS 6 中却显示出完美的 UI。这可能是什么原因呢？

Let me tell you that your code is correct, after some test finally I could fix it, just go to Settings add Social Accounts (Facebook - Twitter - Flickr - Mail), run again your app and you will see the icons. Regards from Cancun!