错误应用程序尝试以模态方式呈现活动控制器Swift

Question

拥有一个带有多个UIViewControllers的UITabBarController。在其中一个控制器内部，当满足某个条件时，我想实例化另一个UIViewController，它是同一个UITabBarController的子节点。 我一直收到这个错误＆＃34; 应用程序尝试以模态方式呈现一个活动控制器＆＃34;但我不明白scheduleNavController是如何处于活动状态的。我在SO上查了几个答案，但我仍然不明白我的错误是什么，我该如何解决呢？ 应用程序的流程如下：WelcomeViewController，LoginViewController，UITabBarController和UITabBarController的子代。

   let storyboard = UIStoryboard(name: "Main", bundle: nil)
   let tabController = storyboard.instantiateViewController(withIdentifier: "CentralTabBarControllerID") as! UITabBarController

 if let viewControllers = tabBarController?.viewControllers {
     let scheduleNavController = viewControllers[1] as! UINavigationController
     let scheduleVC = scheduleNavController.childViewControllers[0] as! Schedule

       tabController.present(scheduleNavController, animated: true, completion: {
          scheduleVC.segmentedControlIndexReceivedFromClaimDetail = self.segmentedControlIndex
             })

        }

Answer 1

感谢Andreas Oetjen建议使用UITabBarController的selectedIndex，我提出了另一个解决方案。但是，我仍然不知道应该如何修复原始问题中的代码以使其正常工作。

 //select index of the UIViewController we want to switch to 
// get the UINavigationController for the tab we want to switch to
// get UIViewController to which we want to pass data 
 self.tabBarController?.selectedIndex = 1
 let scheduleNavController = tabBarController?.viewControllers?[1] as! UINavigationController
 let scheduleVC = scheduleNavController.childViewControllers[0] as! Schedule
 scheduleVC.segmentedControlIndexReceivedFromClaimDetail = self.segmentedControlIndex

//remove the the current UIViewController from which we switch to another controller above.
 let claimDetailNav = tabBarController?.viewControllers?[0] as! UINavigationController
  let claimDetailVC = claimDetailNav.childViewControllers[1] as! ClaimDetail
  claimDetailVC.removeFromParentViewController()