[iOS 15] Header buttons stop responding after pushing and popping a screen over the pager #1189

Environment

• react-native-pager-view 9.0.4 in the repro app; the relevant code (PagerViewProvider.setupView()) is unchanged in 9.0.9
• iOS 15.2 simulator (the reporter also reproduced it on a 15.1 device; newer iOS versions are not affected)
• React Native 0.84.1, New Architecture (Fabric)
• @react-navigation/{native,stack,bottom-tabs,material-top-tabs} v7, react-native-screens 4.27

Description

On iOS 15, after pushing a screen on top of a screen that contains a PagerView and then going back, the React Navigation header buttons (headerLeft / headerRight) stop responding. They never fire again for that screen.

The cause is not React Navigation. On iOS 15 UIHostingController installs SwiftUI's UIKitNavigationBarBridge, which calls -[UINavigationController setNavigationBarHidden:NO] on the enclosing navigation controller whenever the hosting view appears. react-native-screens creates an RNSContainerNavigationController with a hidden bar for the bottom-tab hasTwoStates container; the bridge re-shows an empty UINavigationBar on top of the screen — exactly over the React Navigation header — and that bar swallows every touch there.

Measured with lldb on an iOS 15.2 simulator after push → pop:

Breakpoint trace of the cause (on -[UINavigationController setNavigationBarHidden:animated:], hidden = NO):

#0  -[UINavigationController setNavigationBarHidden:animated:]
#1  SwiftUI.UIKitNavigationBarBridge.hostingControllerWillAppear(animated:)
#2  SwiftUI._UIHostingView.viewControllerWillAppear(...)
#3  SwiftUI.UIHostingController._viewWillAppear(_:)
...
#16 -[RNSScreenContainerView attachScreen:atIndex:]   ← react-native-screens re-attaches the screen on pop

Reproducible Demo

https://github.com/zewillze/react-native-pager-view-ios15-issue

1. Run the repro on an iOS 15.x simulator/device.
2. Tap a list row (pushes Detail inside a @react-navigation/stack).
3. Go back.
4. Tap the "Button" or "+" header button — nothing happens.

The screen structure matters: bottom tabs → stack (with a JS header) → material top tabs (the pager). The bottom-tab container provides the hidden UINavigationController, and the pager's UIHostingController is what triggers the bridge when it re-appears.

Optional check without touches, after step 3 — dump the window hierarchy:

po [[[UIApplication sharedApplication] keyWindow] performSelector:@selector(recursiveDescription)]

Before: a UINavigationBar at (0 47; 428 44) with hidden = NO. After the fix: none.

Proposed fix

Wrap the UIHostingController created in ios/PagerViewProvider.swift so it restores the enclosing navigation bar's hidden state around viewWillAppear.

To keep it easy to drop with iOS 15, the workaround lives in its own file (PagerViewIOS15NavigationBarCompat.swift) and every entry point returns early on iOS 16+ via if #available(iOS 16, *). Deleting that file and replacing the single call site with UIHostingController(...) is all that is needed once iOS 15 support is removed — the same isolation pattern used for the iOS 15 scrollEnabled fix (#1148).

The change is 2 files (+68/−1), preserves 9.0.9's ignoreSafeArea: true behaviour, and I have verified it on an iOS 15.2 simulator. I'll open a PR referencing this issue.