How to persist navigationItem.titleView between screen? - ios

Question

I am using NavigationController to manage three screens. All three screens share a common image as title. I set the image in the viewWillAppear in each VC as follow:
self.navigationItem.titleView = myImageView
The problem is whenever a screen is pushed/popped, the navigation is animated and a new image will come from right or left. I want the image to persist and remain in the middle none-animated.
Is there a way to disable this animation?

Answer 1

It's reproducible, only if you place/setting titleView code in viewWillAppear. it's moving because viewWillAppear called during forth(push) & back(pop) both operation. Set it into viewDidLoad, it will fix this issue
override fun viewDidLoad() {
super.viewDidLoad()
self.navigationItem.titleView = myImageView
}
One more alternate solution for this problem is
var isViewDidLoadCalled = false
override fun viewDidLoad() {
super.viewDidLoad()
isViewDidLoadCalled = true
}
override fun viewWillAppear(_ animated: Bool) {
super. viewWillAppear(animated)
if (isViewDidLoadCalled) {
self.navigationItem.titleView = myImageView
isViewDidLoadCalled = false
}
}
I recommend to use, viewDidLoad to setup your titleView

Answer 2

Another hard but feasible solution is:
You need to use the UINavigationController delegate methods to find out when the UIViewController is being shown. Then for each UIViewController, need to make a boolean variable like isInitialized property, which help you to determine when the UIViewController is being pushed on the stack, or when it's being shown upon back of next view controller.
Your FirstViewController:
func navigationController(_ navigationController: UINavigationController, willShowViewController viewController: UIViewController, animated: Bool) {
if viewController == self {
if self.isInitialized {
var navigationBarAnimation = CATransition()
navigationBarAnimation.duration = 1.5
navigationBarAnimation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseIn)
navigationBarAnimation.type = kCATransitionFade
navigationBarAnimation.subtype = kCATransitionFade
navigationBarAnimation.removedOnCompletion = true
self.navigationController?.navigationBar?.layer?.addAnimation(navigationBarAnimation, forKey: nil)
} else {
self.isInitialized = true;
}
}
}
func navigationController(_ navigationController: UINavigationController, didShowViewController viewController: UIViewController, animated: Bool) {
if viewController == self {
if self.isInitialized {
self.navigationController?.navigationBar?.layer?.removeAllAnimations()
}
}
}
Your SecondViewController:
func navigationController(_ navigationController: UINavigationController, willShowViewController viewController: UIViewController, animated: Bool) {
if viewController == self {
if !self.isInitialized {
var navigationBarAnimation = CATransition()
navigationBarAnimation.duration = 1.5
navigationBarAnimation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseIn)
navigationBarAnimation.type = kCATransitionFade
navigationBarAnimation.subtype = kCATransitionFade
navigationBarAnimation.removedOnCompletion = true
self.navigationController?.navigationBar?.layer?.addAnimation(navigationBarAnimation, forKey: nil)
self.isInitialized = true;
}
}
}
func navigationController(_ navigationController: UINavigationController, didShowViewController viewController: UIViewController, animated: Bool) {
if viewController == self {
if self.isInitialized {
self.navigationController?.navigationBar?.layer?.removeAllAnimations()
}
}
}