iOS 11 large-title navigation bar not collapsing

The Apple guy in the What's new in Cocoa Touch WWDC video said that the new large-title navigation bar will magically hook into the top-level scroll view of the underlying view controller and collapse/expand itself automatically while scrolling up and down. (And by "magically", he probably meant that they failed to monkey patch this functionality into the already embarassing UINavigationController-UINavigationBar-UINavigationitem APIs in a usable way, so they had to resort to hooking into some heuristically chosen scroll view behind the scenes)

Even though I was prepared that this "automatic" collapse/expand wouldn't work if I deviate the slightest from the basic UINavigationController + UITableView/UICollectionView setup, it seems that even in this simplest case it doesn't work as expected.

Here's what I have:

A UITabBarController which contains a UINavigationController, which contains a UIViewController, which has a UITableView as its view. Tapping the first cell in the table will push a second view controller on the navigation stack:

No code, just the storyboard.

I've checked "Prefers large titles" for the navigation bar to activate large titles. Now, if I run the app and scroll up/down on the table view, the navigation bar stays the same - large - size; it doesn't collapse:

However, I've found that if I set the second view controller's navigation item to use the small navigation bar (by setting "Large Title" to the value "Never"), then if I open that page and navigate back, the interactive collapse magically starts working on the first page:

Am I missing something here, or is this feature not working properly? Here's the sample project I'm using: https://github.com/tzahola/iOS-11-Large-Title-Navigation-Bar

And by the way, I'm using the officially released iOS 11, not the betas.

2017-09-23 Update: I've sent a bug report to Apple, and opened a ticket on openradar.me: http://www.openradar.me/radar?id=5017601935671296

Solution 1:

If there is any other view in addition to tableView, also make sure tableView is on the top of that view(s), right under the Safe Area:

Solution 2:

Good news! I've just figured out that if I set "Large Titles" to "Never" on the storyboard, and then set it via code, then it works:

- (void)viewDidLoad {
    [super viewDidLoad];
    self.navigationItem.largeTitleDisplayMode = UINavigationItemLargeTitleDisplayModeAutomatic;
}

Seems like Apple forgot to handle the case when the navigation item has its largeTitleDisplayMode set via the Interface Builder.

So until they fix this issue, leave "Large Titles" as "Never" on storyboards, and set them via code in viewDidLoad.

You just need to do that to the first view controller. Subsequent view controllers honor the value in storyboard.

Solution 3:

Or instead of changing anything in storyboard, do this:

override func viewDidLoad() {
    super.viewDidLoad()
    if #available(iOS 11.0, *) {
        self.navigationItem.largeTitleDisplayMode = .never
        self.navigationItem.largeTitleDisplayMode = .always
    }
}

No matter which language!

This is because large titles on navigation item decides whether or not to collapse on the basis of large title behaviour on previous screen navigation item title.