Why does popping UIViewController change navigationItem's titleTextAttributes?

Question

I'm building a social network that allows users to navigate from one profile to the next, by viewing who they follow. For simplicity, I created a test project with two view controllers: ViewController and SecondViewController.

Each view controller has a button that fires an IBAction to instantiate the next view controller. That view is then pushed on the navigation stack. A user can do this as long as there is another viewController to push. But when they start returning/popping is when I have issues.

Here's ViewController:

class ViewController: UIViewController {
    @IBOutlet weak var pageNumberLabel: UILabel!

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)

        self.navigationItem.title = "First"
        setUp()
    }

    func setUp() {
        print("Setup 1")

        let navBarAppearance = self.navigationController!.navigationBar
        navBarAppearance.setBackgroundImage(UIImage(), for: .default)
        navBarAppearance.shadowImage = UIImage()
        navBarAppearance.barStyle = .black
        navBarAppearance.isTranslucent = true
        navBarAppearance.tintColor = .white
        navBarAppearance.titleTextAttributes = [NSAttributedString.Key.foregroundColor : UIColor.white]
        self.navigationController?.view.backgroundColor = UIColor.lightGray
    }

    @IBAction func pushSecondViewController() {
        if let vc = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "secondVC") as? SecondViewController {
            print("-")
            self.navigationController?.pushViewController(vc, animated: true)
        }
    }
}

Here's SecondViewController:

class SecondViewController: UIViewController {
    @IBOutlet weak var pageNumberLabel: UILabel!

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)

        self.navigationItem.title = "Second"
        setUp()
    }

    func setUp() {
        print("Setup 2")

        let navBarAppearance = self.navigationController!.navigationBar
        navBarAppearance.isTranslucent = false
        navBarAppearance.barTintColor = .white
        navBarAppearance.tintColor = .blue
        navBarAppearance.barStyle = .black
        navBarAppearance.titleTextAttributes = [NSAttributedString.Key.foregroundColor : UIColor.blue]
    }

    @IBAction func pushFirstViewController() {
        if let vc = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "firstVC") as? ViewController {
            print("-")
            self.navigationController?.pushViewController(vc, animated: true)
        }
    }
}

When SecondViewController is popped and ViewController is presented, the navigationTitle stays UIColor.blue. However, if I swipe from SecondViewController to ViewController, the title correctly changes colors.

Why is this?

take a look in this link stackoverflow.com/questions/42618802/… — Bathant Hegazy

Richard Poutier Richard Poutier · Accepted Answer · 2018-11-16T19:33:01

I found a workaround solution to this issue...originally posted here. I put the following code in my setUp() function for my navigation bar.

let titleView = UIView(frame: CGRect(x: 0, y: 0, width: 100, height: 50))
titleView.backgroundColor = UIColor.clear
let titleLabel = UILabel(frame: CGRect(x: 0, y: 0, width: 100, height: 50))
titleLabel.textAlignment = .center
titleLabel.text = [My View Name]
titleLabel.textColor = .blue
titleView.addSubview(titleLabel)
self.navigationItem.titleView = titleView
self.navigationItem.title = [My View Name]

Why does popping UIViewController change navigationItem's titleTextAttributes?

1 Answers