弹出一个ViewController后如何判断栈顶的ViewController是不是特定的？

Question

假设我目前在 BaseViewController。我可以从其他 2 个视图控制器（比如 A 和 B）接近这个视图控制器 class。所以当我弹出 BaseViewController 时，如何检查堆栈顶部是否存在 A 或 B？下面是我的代码（在 BaseViewController 内）：

func goToAOrBViewController {
   // If after popping viewController is A do this
   navigationController.popViewController(animated: true)
   // Id after popping viewController is B do this
   // Instantiate B and push it
}

Answer 1

有很多方法可以做到这一点

第一种也是最简单的方法

    func visibleViewController() -> UIViewController? {
        let appDelegate = UIApplication.shared.delegate
        if let window = appDelegate!.window {
            return window?.visibleViewController
        }
        return nil
    }

    func goToAOrBViewController {
       // If after popping viewController is A do this
       navigationController.popViewController(animated: true)
       if visibleViewController() == viewControllerA{
           //Do stuff for A
       }else{
           //Do stuff for B
       }
    }

第二种明显的方法

    let topController = UIApplication.sharedApplication().keyWindow?.rootViewController
    if topController == viewControllerA {
        //Do stuff for A
    }else{
        //Do stuff for B
    }

Answer 2

您可以同时弹出和推送视图控制器。

未测试：

navigationController?.viewControllers.removeLast()
let topVC = navigationController?.viewControllers.last

if topVC == A {
  navigationController?.viewControllers.append(A)
  navigationController?.setViewControllers(A, animated: false)
} else {
  navigationController?.viewControllers.append(B)
  navigationController?.setViewControllers(B, animated: false)
}

Answer 3

里面 BaseViewController class:

func goToAOrBViewController() {
   guard let navigationController = self.navigationController else { return }
   navigationController.popViewController(animated: false)
   guard let viewController = navigationController.topViewController else { return }
   if viewController is ViewControllerA {
      // Do something for A
   } else if viewController is ViewControllerB {
      // Do Something for B
   }
   // You need not put else-if case if you are sure BaseVC is reachable from A and B only (just use else)
}

弹出一个ViewController后如何判断栈顶的ViewController是不是特定的？

How to check after popping a ViewController, the ViewController on top of the stack, is a particular one?

uiviewcontroller

uinavigationcontroller

swift