Navigation Controller¶

Navigation Stack¶

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. https://sarunw.com/posts/uinavigationbar-changes-in-ios13/

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

]

SO

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.

https://stackoverflow.com/questions/28733936/change-color-of-back-button-in-navigation-bar

https://www.youtube.com/watch?v=7KdRpFEOG9I

Navigation Items¶

SO

Try to hide titleView label

self.navigationItem.titleView = UIView()

Quirks¶

Navigation bar¶

Large title text navigation SO

navigation bar glitches

https://stackoverflow.com/questions/69111478/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¶

https://stackoverflow.com/questions/26132658/pop-2-view-controllers-in-nav-controller-in-swift

https://developer.apple.com/forums/thread/134078

References¶

https://dmtopolog.com/navigation-bar-customization/