Navigation Bar Large Title transition delegate

Question

I have enabled Large Title in my navigation bar with automatic Display Mode, so that it shrinks when user scrolls. Is there a way to get notified when this transition happens? I didn't found any delegate method for this. I have a Right Bar Button Item with long label which I'd like to hide when Large Title gets shrunk so that the title is perfectly centered.

score 3 · Accepted Answer · answered May 24 '19 at 19:44

Apparently there's no delegate nor any other official way to be notified about this. So my workaround is using ScrollViewDelegate:

extension ViewController: UIScrollViewDelegate {
    func scrollViewDidScroll(_ scrollView: UIScrollView) {
        if let height = navigationController?.navigationBar.frame.size.height, height == 44 {
            // handle small title
        }
        else {
            // handle large title
        }
    }
}

This doesn't work on iPad as the height of navbar is different, but that's intended in my case.

Also keep in mind that scrollViewDidScroll gets called XX times for a single small scroll, so before doing any updates, check they haven't been done already.

You could check the same thing inside `viewDidLayoutSubviews`. It is being called a little bit less often than `scrollViewDidScroll`. — Starsky, Sep 04 '20 at 09:30

Navigation Bar Large Title transition delegate

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