观察UINavigationController navigationBar显示/隐藏

Question

I have a UINaviationController added through storyboard with selected options like Hide Bars On Tap etc. I was wondering what is the best solution to react to navigationBar and toolbar shows/hides. I tried overriding UINavigationController and methods like setNavigationBarHidden(_ hidden: Bool, animated: Bool) , but this doesn't get called when you tap to hide. I think it's probably possible to observe some variable, but I'm not sure which one and if it will work.

Answer 1

You can try

var ob:NSKeyValueObservation?

override func viewDidLoad() {
    super.viewDidLoad()

    ob = self.navigationController?.observe(\.navigationBar.isHidden, options: [.new], changeHandler: { (nav, ob) in
        print("ok")
    })
}