Understanding Bar Button Items in Navigation Controllers: The Solution to Disappearing Buttons

Introduction

In this article, we will delve into the world of navigation controllers and bar button items. We’ll explore the problem of disappearing bar button items and how to resolve it.

To begin, let’s create a simple navigation controller setup with bar button items. First, we need to add a navigation controller to our view controller hierarchy:

// Create a new project in Xcode
// Set up the storyboard for our view controller

Next, we’ll set up the navigation controller and add two bar button items. The first one will be an image and the second one will be text.

A navigation controller is a powerful tool in iOS development that allows us to manage the hierarchy of our app’s view controllers. It provides a stack of view controllers that can be easily navigated between using the back button or push segue.

// Define the navigation controller
import UIKit

class ViewController: UIViewController, UINavigationControllerDelegate {
    let navigationController = UINavigationController()

    override func viewDidLoad() {
        super.viewDidLoad()
        // Set up the navigation bar appearance
        navigationController.navigationBar.isTranslucent = false
        navigationController.navigationBar.barTintColor = UIColor(red: 0.94, green: 0.94, blue: 0.94, alpha: 1)
    }
}

Understanding Bar Button Items

Bar button items are a crucial part of the navigation controller’s interface. They provide a way to interact with our app’s user interface and can be used for various purposes such as navigating between view controllers or displaying additional information.

// Define the bar button item
import UIKit

class ViewController: UIViewController, UINavigationControllerDelegate {
    let barButtonItem = UIBarButtonItem(image: UIImage(named: "barbuttonitem"), style: .plain, target: self, action: #selector(barButtonItemAction))
}

The Problem of Disappearing Bar Button Items

In the original question, the developer experienced an issue with their navigation controller’s bar button items disappearing at random times. This problem was not caused by any code that was intentionally hiding the buttons.

// The problem occurs when using certain view controllers
import UIKit

class ViewController: UIViewController, UINavigationControllerDelegate {
    let barButtonItem = UIBarButtonItem(image: UIImage(named: "barbuttonitem"), style: .plain, target: self, action: #selector(barButtonItemAction))

    override func viewDidLoad() {
        super.viewDidLoad()
        // Set up the navigation controller's delegate and view controller hierarchy
        navigationController.delegate = self
        viewControllers.append(self)
    }
}

The Solution: Understanding TintColor

The answer to this problem lies in understanding the UINavigationBar.appearance().tintColor property. This property determines the color of the navigation bar.

// Set up the navigation bar's appearance
UINavigationBar.appearance().tintColor = UIColor(red: 0.94, green: 0.94, blue: 0.94, alpha: 1)

However, this property alone does not explain why the bar button items disappeared in certain situations.

The Connection to MFMailComposeViewController

The issue is related to the MFMailComposeViewController class. This view controller provides a way to compose an email and can affect the appearance of other UI elements in our app.

// Use MFMailComposeViewController to compose an email
import UIKit
import MessageUI

class ViewController: UIViewController, UINavigationControllerDelegate, MFMessageComposeViewControllerDelegate {
    let barButtonItem = UIBarButtonItem(image: UIImage(named: "barbuttonitem"), style: .plain, target: self, action: #selector(barButtonItemAction))

    override func viewDidLoad() {
        super.viewDidLoad()
        // Set up the navigation controller's delegate and view controller hierarchy
        navigationController.delegate = self
        viewControllers.append(self)
    }

    @objc func barButtonItemAction() {
        let mailViewController = MFMailComposeViewController()
        mailViewController.mailComposeDelegate = self
        present(mailViewController, animated: true, completion: nil)
    }
}

The Solution: Setting the TintColor of SKStoreProductViewController

To fix this issue, we need to set the viewTintColor property of the SKStoreProductViewController. This property determines the color of the view controller’s content.

// Set up the SKStoreProductViewController
import StoreKit

class ViewController: UIViewController, UINavigationControllerDelegate {
    let barButtonItem = UIBarButtonItem(image: UIImage(named: "barbuttonitem"), style: .plain, target: self, action: #selector(barButtonItemAction))

    override func viewDidLoad() {
        super.viewDidLoad()
        // Set up the navigation controller's delegate and view controller hierarchy
        navigationController.delegate = self
        viewControllers.append(self)

        let productViewController = SKStoreProductViewController()
        productViewController.product = SKStoreProduct(productID: "your_product_id")
        productViewController.view.tintColor = UIColor(red: 0.94, green: 0.94, blue: 0.94, alpha: 1)
    }
}

By setting the viewTintColor property of the SKStoreProductViewController, we ensure that the bar button items are not affected by the navigation bar’s tint color.

Conclusion

In this article, we explored the issue of disappearing bar button items in a navigation controller. We discovered that the problem was related to the MFMailComposeViewController class and its effect on the navigation bar’s appearance. By setting the viewTintColor property of the SKStoreProductViewController, we were able to fix this issue and ensure that our app’s bar button items remain visible.

Additional Tips and Variations

To customize the appearance of your navigation controller, you can use the UINavigationBar.appearance() method.
To hide or show specific bar button items, you can use the UIBarButtonItem initializer methods.
To create a custom view for your navigation controller, you can subclass UINavigationController and override its viewDidLoad method.

By following these tips and variations, you can further customize your app’s UI and improve its overall appearance.

Last modified on 2023-09-25

Understanding Bar Button Items in Navigation Controllers