iOS 7 UIActivityViewController电子邮件附件

我在这里回顾了一堆帖子,大量的在线教程/示例代码,我很难过.在我的应用程序中,我显示iOS7本身提供的UIActivityController与我的应用程序(AirDrop和邮件)相适应的共享选项没有问题.

我遇到的具体问题是当用户选择通过邮件共享选项时,将保存的文档附加到电子邮件中.消息正文正在设置为文本,但附件是MIA.相关代码是：

//生成要为当前显示的记录共享的XML文件…
    NSURL * url = [self createShareFile];

UIActivityViewController *controller = [[UIActivityViewController alloc] initWithActivityItems:@[@"Data shared from my app.",url] applicationActivities:nil];

// Filter out the sharing methods we're not interested in....
controller.excludedActivityTypes = @[UIActivityTypePostToTwitter,UIActivityTypePostToFacebook,UIActivityTypePostToWeibo,UIActivityTypemessage,UIActivityTypePrint,UIActivityTypeCopyToPasteboard,UIActivityTypeAssignToContact,UIActivityTypeSaveToCameraRoll,UIActivityTypeAddToReadingList,UIActivityTypePostToFlickr,UIActivityTypePostToVimeo,UIActivityTypePostToTencentWeibo];

// Now display the sharing view controller.
[self presentViewController:controller animated:YES completion:nil];

我错过了什么？我的文件正确创建,内容正确,NSURL对象包含文件的正确路径.

谢谢！

return [NSURL URLWithString:[docFile StringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];

return [NSURL fileURLWithPath:docFile];