UINavigationBar Large Title doesn't appear when scroll view up - ios

Question

I have implemented a feature, when you press on a UITabBar icon and viewController1 scrolls up using its UIScrollView. It works perfectly, but if I scroll view down and stop somewhere, then switch to another viewController2, then get back to viewController1 and press tabBar icon - the viewController1 will scroll up, but Large Title will never be showed, and I should press tabBar icon one more time to show it:
The code I use for scroll up the VC1:
private var biggestTopSafeAreaInset: CGFloat = 0
override func viewSafeAreaInsetsDidChange() {
super.viewSafeAreaInsetsDidChange()
self.biggestTopSafeAreaInset = max(view.safeAreaInsets.top, biggestTopSafeAreaInset)
}
func tabBarController(_ tabBarController: UITabBarController, didSelect viewController: UIViewController) {
if tabBarController.selectedIndex == 0 {
let navigationVC = viewController as? UINavigationController
let firstVC = navigationVC?.viewControllers.first as? CurrencyViewController
guard let scrollView = firstVC?.view.subviews.first(where: { $0 is UIScrollView }) as? UIScrollView else { return }
if traitCollection.verticalSizeClass == .compact {
scrollView.setContentOffset(CGPoint(x: 0, y: -view.safeAreaInsets.top, animated: true)
} else {
scrollView.setContentOffset(CGPoint(x: 0, y: -biggestTopSafeAreaInset, animated: true)
}
}
}
I tried to track biggestTopSafeAreaInset in different stages of VC1 life, but it always has the same number - 196.0. But then why it doesn't scroll till the Large Title after viewControllers switch?

Answer 1

in your tableView set contentInsetAdjustmentBehavior to never
tableView.contentInsetAdjustmentBehavior = .never
in controller update the ui of navigation bar again
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
DispatchQueue.main.async { [weak self] in
self?.navigationController?.navigationBar.sizeToFit()
}
}
here is the navigation controller
class BaseNavigationController: UINavigationController {
override func viewDidLoad() {
super.viewDidLoad()
if #available(iOS 15.0, *) {
let scrollAppearance = UINavigationBarAppearance()
scrollAppearance.shadowColor = .white
scrollAppearance.backgroundColor = .white
let navigationBarAppearance = UINavigationBarAppearance()
navigationBarAppearance.configureWithDefaultBackground()
navigationBarAppearance.backgroundColor = .white
navigationBarAppearance.largeTitleTextAttributes = [
NSAttributedString.Key.font: UIFont.systemFont(ofSize: 26),
NSAttributedString.Key.foregroundColor: UIColor.black
]
navigationBarAppearance.titleTextAttributes = [
NSAttributedString.Key.font: UIFont.systemFont(ofSize: 17),
NSAttributedString.Key.foregroundColor: UIColor.black
]
UINavigationBar.appearance().backIndicatorImage = UIImage(named: "back-arrow")
UINavigationBar.appearance().standardAppearance = navigationBarAppearance
UINavigationBar.appearance().compactAppearance = navigationBarAppearance
UINavigationBar.appearance().scrollEdgeAppearance = scrollAppearance
navigationBar.tintColor = .black
navigationBar.prefersLargeTitles = true
navigationBar.isTranslucent = false
navigationItem.largeTitleDisplayMode = .automatic
} else {
navigationBar.largeTitleTextAttributes = [
NSAttributedString.Key.font: UIFont.systemFont(ofSize: 26),
NSAttributedString.Key.foregroundColor: UIColor.black
]
navigationBar.titleTextAttributes = [
NSAttributedString.Key.font: UIFont.systemFont(ofSize: 17),
NSAttributedString.Key.foregroundColor: UIColor.black
]
navigationBar.tintColor = .black
navigationBar.prefersLargeTitles = true
navigationBar.isTranslucent = false
navigationItem.largeTitleDisplayMode = .automatic
navigationBar.barTintColor = .white
}
}
override var preferredStatusBarStyle: UIStatusBarStyle {
return .darkContent
}
}
here is the Tabbar Controller
class TabbarController:UITabBarController {
override func viewDidLoad() {
super.viewDidLoad()
let c1 = C1()
let c2 = C2()
let c3 = C3()
c1.tabBarItem = UITabBarItem(title: "Home", image: UIImage(named: "home786"), tag: 0)
c1.tabBarItem.tag = 0
let nav1 = BaseNavigationController(rootViewController: c1)
c2.tabBarItem = UITabBarItem(title: "Setting", image: UIImage(named: "home786"), tag: 0)
c2.tabBarItem.tag = 1
let nav2 = BaseNavigationController(rootViewController: c2)
c2.tabBarItem = UITabBarItem(title: "User", image: UIImage(named: "home786"), tag: 0)
c2.tabBarItem.tag = 2
let nav3 = BaseNavigationController(rootViewController: c3)
viewControllers = [nav1,nav2,nav3]
selectedViewController = nav1
tabBarController?.viewControllers?.first?.view.backgroundColor = .red
}
}

Answer 2

Try to add this in viewDidLoad:
view.addSubview(UIView())
this single line block large title navigation Bar... I don't Know why, but this trick fix momentarily the issue...

Answer 3

After some research I found out what can fix my problem. If you call this method with a small delay in tabBarController didSelect then it will be possible to see a Large Title after switching viewControllers. But I still can't figure out exactly why it happened...
DispatchQueue.main.asyncAfter(deadline: .now() + 0.2) {
navigationVC?.navigationBar.sizeToFit()
}