MFMailComposeViewController在呈现后立即解除

Question

它适用于iPhone，此问题仅发生在iPad（iOS7）上。太奇怪了。

我收到了这个错误日志：

  

_serviceViewControllerReady：error：Error Domain = _UIViewServiceInterfaceErrorDomain Code = 0“无法完成操作。（_UIViewServiceInterfaceErrorDomain error 0。）”

我做了一些搜索，一些答案说它可能与定制的UINavigationBar外观有关。

就我而言，我正在使用导航控制器并更改其颜色和状态栏颜色

在info.plist中：set View controller-based status bar appearance为NO

然后在appDelegate

[[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleLightContent]; 

我尝试评论该行，问题仍然存在。所以我认为这不是问题所在。

这是我的发送电子邮件代码和代理

Class mailClass = (NSClassFromString(@"MFMailComposeViewController"));
if (mailClass != nil) {
    if ([mailClass canSendMail]) {
        MFMailComposeViewController *mailPicker = [[MFMailComposeViewController alloc] init];
        mailPicker.mailComposeDelegate = self;
        NSString *emailbody = @"";
        [mailPicker setSubject: subject];
        NSArray *toRecipients = [NSArray arrayWithObject: recipient];
        [mailPicker setToRecipients: toRecipients];
        [mailPicker setMessageBody:emailbody isHTML:NO];
        [self presentViewController:mailPicker animated:YES completion:nil];
    } 
} 

- (void)mailComposeController:(MFMailComposeViewController *)controller
      didFinishWithResult:(MFMailComposeResult)result error:(NSError *)error {
    [self dismissViewControllerAnimated:YES completion:nil];
}