在AppDelegate中设置barButtonItem

Question

How can I set barButtonItem in AppDelegate ? Now I have this code:

func presentDetailViewController(_ hallID: String) {

    let storyboard = UIStoryboard(name: "Main", bundle: nil)

    let navVC = UINavigationController()

    let newDetailVC = storyboard.instantiateViewController(withIdentifier: "newDetailVC") as! NewDetailTableViewController

    newDetailVC.hallID = hallID

    navVC.viewControllers = [newDetailVC]

    let backItem = UIBarButtonItem(title: "Back", style: .plain, target: self, action: #selector(AppDelegate.goToMainVC))
    navVC.navigationItem.setRightBarButton(backItem, animated: true)

    window?.rootViewController = navVC 

    window?.makeKeyAndVisible()

}

@objc func goToMainVC() {

    let storyboard = UIStoryboard(name: "Main", bundle: nil)

    let navVC = UINavigationController()

    let mainVC = storyboard.instantiateViewController(withIdentifier: "MainVC") as! PhotoStudiosViewController

    navVC.viewControllers = [mainVC]

    window?.rootViewController = navVC

    window?.makeKeyAndVisible()

}

let backItem = UIBarButtonItem(title: "Назад", style: .plain, target: self, action: #selector(AppDelegate.goToMainVC)) navVC.navigationItem.setRightBarButton(backItem, animated: true)

This line not helped me and barButtonItem still not appear. How can I create backButton with my action func goToMainVC ?

Answer 1

You don't set the navigation item to navigation controller rather you set the navigation item to the navigation bar of viewController

so change your code as

let newDetailVC = storyboard.instantiateViewController(withIdentifier: "newDetailVC") as! NewDetailTableViewController
let backItem = UIBarButtonItem(title: "Back", style: .plain, target: self, action: #selector(AppDelegate.goToMainVC))
//navVC.navigationItem.setRightBarButton(backItem, animated: true) this is the issue
newDetailVC.navigationItem.setRightBarButton(backItem, animated: true)

Hope this helps