将新视图控制器添加到当前堆栈

Question

我正在将一个 ViewController 插入到我当前的堆栈中。并尝试像这样执行 popviewcontroller。

 var viewControllersArray: [UIViewController] = self.navigationController!.viewControllers


    if(dm.isLoginViewLoaded)
    {
        print("Login view already loaded")

    }

    else
    {
        print("Login view havent load before")
        let myviewcontroller:LoginViewController=UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "LOGIN") as! LoginViewController
        let index=viewControllersArray.count-2
        viewControllersArray.insert(myviewcontroller, at: index)
        // update navigationController viewControllers
        self.navigationController!.setViewControllers(viewControllersArray, animated:false)

    }
    self.navigationController?.popViewController(animated: true)

但是为什么我不能实现我想要做的事情。即使在满足我的视图控制器的第二个条件下，总是推送到根视图控制器。我想在我当前的视图控制器和根视图控制器之间添加一个新的视图控制器，并执行弹出操作。请帮我。 谢谢

Answer 1

我认为您只是“错误计算”了数组位置。您的索引应该是：

let index = viewControllersArray.count - 1   // *not* -2

但是，这可能是一个更“健壮”的方法：

@IBAction func popToLogin(_ sender: Any) {

    if let navVC = self.navigationController {

        var bFoundLogin = false

        var viewControllersArray = navVC.viewControllers

        for vc in viewControllersArray.reversed() {
            if vc is LoginViewController {
                // we found LoginViewController in stack, so
                //  pop to it (even if it's multiple levels back)
                bFoundLogin = true
                navVC.popToViewController(vc, animated: true)
                // found it, so break out of the for loop
                break
            }
        }

        if !bFoundLogin {

            // we didn't find LoginViewController in stack, so
            //  replace current VC with LoginVC

            //if let loginVC = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "LOGIN") as? LoginViewController {
            if let loginVC = UIStoryboard(name: "AnimConstraints", bundle: nil).instantiateViewController(withIdentifier: "LOGIN") as? LoginViewController {

                // insert loginVC before last item
                viewControllersArray.insert(loginVC, at: viewControllersArray.count - 1)
                // set the NavVC's array of controllers
                navVC.setViewControllers(viewControllersArray, animated: false)
                // pop back one level (to our inserted loginVC)
                navVC.popViewController(animated: true)

            }

        }

    }

}

使用循环在堆栈中“查找”LoginViewController 允许您“弹出”它，即使它不是“行中的下一个”，也无需跟踪您的 dm.isLoginViewLoaded（除非您'正在其他地方使用）。

Answer 2

试试这个代码：

let arrController:[UIViewController] = (self.navigationController?.viewControllers)!//array of all controllers in navigation stack
    for vc in arrController
    {
      if (type(of: vc)  == type(of: LoginViewController
))//check exist or not
      {
        self.navigationController?.popToViewController((arrController[(arrController.index(of: vc))!]), animated: true)
      }
    }