应用内电子邮件和导航栏相互冲突

Question

这是我用来展示应用内电子邮件的代码：

MFMailComposeViewController *mailer = [[MFMailComposeViewController alloc] init];
    mailer.mailComposeDelegate = self;
    [mailer setSubject:@"Look at this Job I found!"];
    NSString *emailBody = [NSString stringWithFormat:@"Look at this Job I found:\n%@ (%@)\nSalary Rage: %@-%@\n Located in %@.\n%@\n%@.\n", _positionTitleLabel.text, _organizationNameLabel.text,_minSalaryLabel.text,_maxSalaryLabel.text,_locationLabel.text,_startDateLabel.text,jobsy.url];
    [mailer setMessageBody:emailBody isHTML:NO];
    [self presentViewController:mailer animated:YES completion:nil];

这是结果/问题：http://i.imgur.com/mwWzVxj.png