Navigation_Controller

To check for which UINavigation ViewController is holding or presenting to present alerts sometimes we need to verify whether it internally is been hold by the UINavigationStack or parent-child relationships.

if let vc = presentingViewController.presentingViewController {
	vc.present(alertViewController, animated: true)
} 
else {
	presentingViewController.present(alertViewController,
	animated: true)
}

iOS 15

Need to use UINavigationBarAppearance for updating the UINavigation Bar properties.

Before iOS 15

private let navigationController: UINavigationController = {

	let navigationController = UINavigationController()
	let navigationBar = navigationController.navigationBar
	
	navigationBar.backgroundColor = UIColor(red: 0.93, green: 0.22, blue: 0.28, alpha: 1.00)
	appearance.titleTextAttributes = [
		NSAttributedString.Key.font: UIFont(name: "Avenir-Medium", size: 32.0)!,
		NSAttributedString.Key.foregroundColor: UIColor.white
	]
	
	return navigationController
}()

After iOS 15

private let navigationController: UINavigationController = {

	let navigationController = UINavigationController()
	let navigationBar = navigationController.navigationBar
	let appearance = UINavigationBarAppearance()
	
	appearance.configureWithOpaqueBackground()
	appearance.backgroundColor = UIColor(red: 0.93, green: 0.22, blue: 0.28, alpha: 1.00)
	appearance.titleTextAttributes = [
		NSAttributedString.Key.font: UIFont(name: "Avenir-Medium", size: 32.0)!,
		NSAttributedString.Key.foregroundColor: UIColor.white
	]
	
	navigationBar.standardAppearance = appearance;
	navigationBar.scrollEdgeAppearance = navigationBar.standardAppearance	
	
	return navigationController
}()

Apple Dev forums

isTranslucent property being added in iOS 13 which has different behavior with UI NavigationBar background color.
sarunw | navigationbar changes in iOS 13

Text Attributes not updating

You need to update the property using UINavigationBarAppearance or else it won't work with whatever text attribute being set towards the title.

//This is the line that doesnt work :( 
navigationBar.titleTextAttributes = [NSAttributedString.Key.foregroundColor: UIColor.white

You can use object of UINavigationBarAppearance & update the code. It could also depend on whether you're using preferLargeTitle property on navigation bar.


let appearance = UINavigationBarAppearance()
appearance.titleTextAttributes = [

	NSAttributedString.Key.font: UIFont(name: "Avenir-Medium", size: 32.0)!,

	NSAttributedString.Key.foregroundColor: UIColor.white

]

Theming UIBarButtons

As my fellow media fanatic mentor helped me once with the UINavigationBar or whatever apple UIKit framework has renamed it to now.
We need to set the parent ViewController navigation property rather than changing the child UI ViewController class.
It makes sense but yes the documentation or my understanding of documentation could have been better.

let backItem = UIBarButtonItem(title: "Back", style: .plain, target: nil, action: nil)
backItem.tintColor = UIColor.red
navigationItem.backBarButtonItem = backItem

Here is his snippet of Gitlab Merge Request Code review comment.


this is the proper way to theme the back button that's visible sun the nav bar when viewing the `FieldMetaType ListViewController`.

it seems odd that a change in a different file would be the fix, but back bar button items are usually owned by the view controller that's below the currently visible view controller in a navigation controller. this actually makes sense tho when you consider that the back button's content is actually driven by the previous view controller's content.

we're only showing the back button, but if there was a back button title, we would want it to be set by the view controller that already knows title. and that's exactly what `UINavigationItem` does for us, allows us to configure everything related to this view controller's navigation bar content and behavior (which is only used if this view controller is used inside of a `UINavigationController`).

even though `UINavigationItem` itself doesn't represent a distinct UI component, it's an abstraction that is used within the specific context of push/pop style navigation.

SO | change-color-of-back-button-in-navigation-bar

Youtube video

SO | hide-navigation-title-but-show-its-title-as-back-button-in-next-view-contr

Try to hide titleView label

self.navigationItem.titleView = UIView()

Quirks

Large title text navigation
SO

navigation bar glitches

SO | ios 15 navigation bar transparent

Swap ViewController

Swap or Replace View Controllers.

extension UINavigationController {
    func swap(currentViewController: UIViewController,
              newViewController: UIViewController,
              animated: Bool = false) {
        var controllerStack = self.viewControllers
        if let index = controllerStack.firstIndex(of: currentViewController) {
            controllerStack[index] = newViewController
        }
        setViewControllers(controllerStack, animated: animated)
    }

Pop View Controllers

SO | pop-2-view-controllers-in-nav-controller

apple dev | Pop View Controllers

References

navigation-bar-customization

Navigation_Controller

Navigation Controller

Navigation Stack