MFMessageComposeViewController - 在ios7中发送短信后卡住

Question

使用 MFMessageComposeViewController 在我的项目中从手机发送短信（它正常工作）后，我无法返回应用或按取消。相反我被困在Apple短信界面，我无法做任何其他事情然后重启应用。我是否会错过didFinishWithResult中的某些内容，还是可能是其他内容？感谢

 - (IBAction)sendSMS:(id)sender {
    MFMessageComposeViewController *controller =
    [[[MFMessageComposeViewController alloc] init] autorelease];


   if([MFMessageComposeViewController canSendText])
  {
      NSString *str= @"Hi";
      controller.body = str;
       controller.recipients = [NSArray arrayWithObjects:
                             @"", nil];
       controller.delegate = self;


      [self dismissViewControllerAnimated:YES
                               completion:nil];

       [self presentViewController:controller animated:YES completion:nil];
    }

 }


- (void)messageComposeViewController:(MFMessageComposeViewController *)controller didFinishWithResult:(MessageComposeResult) result
{
    switch (result) {
        case MessageComposeResultCancelled:
            break;

        case MessageComposeResultFailed:
        {
            UIAlertView *warningAlert = [[UIAlertView alloc] initWithTitle:@"Error" message:@"Failed to send SMS!" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
            [warningAlert show];
            break;
        }

        case MessageComposeResultSent:
            break;

        default:
            break;
    }

    [self dismissViewControllerAnimated:YES completion:nil];
}