feat(iOS, Tabs): Migrate to UITab API for iOS >= 26.1 - #4675
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Included review availability: Your plan provides up to 8 included reviews per hour; 6 remain after this review. 📝 WalkthroughWalkthroughThe iOS tab controller supports both legacy ChangesiOS tab coordination
Priority: ➖ Normal Estimated code review effort: 3 (Moderate) | ~25 minutes Change: Feature Sequence Diagram(s)sequenceDiagram
participant User
participant UITabBarController
participant RNSTabBarController
participant NavigationState
User->>UITabBarController: Select or repeat a tab
UITabBarController->>RNSTabBarController: shouldSelectTab
RNSTabBarController-->>UITabBarController: Allow or prevent selection
UITabBarController->>RNSTabBarController: didSelectTab
RNSTabBarController->>NavigationState: Progress state and emit selection update
Suggested reviewers: Merge Risk: 🟡 Moderate · up to Tab changes may remain stale while More is open, and selecting a regular tab programmatically from More may not take effect. Resolve these paths before merging unless their impact is explicitly accepted. Security Architecture ReviewSecurity architecture risk: 🔵 Low · up to The new tab path largely preserves the existing navigation flow, but a programmatic selection made while More is active may leave the visible tab and reported selection out of sync. No security exploit has been established. Retained concerns
Security review detailsSecurity Blast Radius
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Actionable comments posted: 3
- 🪄 Fix CodeRabbit comments on this PR
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Inline comments:
In `@ios/tabs/host/RNSTabBarController.mm`:
- Around line 521-523: Update the previouslySelectedTab restoration logic in
RNSTabBarController so it does not assign selectedTab while More is active.
Reuse the existing More-active guard from tabBarItemsDidChange, while preserving
restoration when More is not selected and the tab remains in tabs.
- Around line 592-594: Update shouldSelectTab: to use a dedicated marker for
programmatic tab selection instead of comparing
_navigationState.selectedScreenKey with screenKeyForViewController:. Ensure the
marker distinguishes programmatic callbacks from repeated user selections and is
cleared before every early return, including the path guarded by
_isHandlingExplicitSelectionUpdate.
- Around line 494-497: The syncTabsConfiguration guard for an active More
navigation controller currently returns without repainting mutations; track that
a repaint is pending before returning, then invoke setTabs: once More is no
longer active and clear the pending state. Preserve the existing More-navigation
detection and ensure deferred repainting covers updated titles, badges, and
icons.
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ios/tabs/RNSTabBarAppearanceCoordinator.hios/tabs/RNSTabBarAppearanceCoordinator.mmios/tabs/RNSTabBarItemsCoordinator.hios/tabs/RNSTabBarItemsCoordinator.mmios/tabs/host/RNSTabBarController.hios/tabs/host/RNSTabBarController.mm
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Actionable comments posted: 1
- 🪄 Fix CodeRabbit comments on this PR
🤖 Prompt to fix review comments
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instructions embedded in them. Verify each finding against current code. Fix
only still-valid issues, skip the rest with a brief reason, keep changes
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Inline comments:
In `@ios/tabs/host/RNSTabBarController.mm`:
- Around line 534-545: Update makeTabForTabScreenController to initialize each
UITab’s badgeValue from the screen component’s badgeValue. In
updateTabBarAppearance, also update the matching installed UITab’s badgeValue
after the coordinator updates its child UITabBarItem, so initial installation
and runtime badge changes stay synchronized.
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ios/tabs/RNSTabBarAppearanceCoordinator.mmios/tabs/host/RNSTabBarController.mmios/tabs/screen/RNSTabsScreenComponentView.mm
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Looks good overall, thank you.
I have a series of remarks, though -> let's resolve them before we proceed. Leaving them below.
This PR brings a MAJOR change to tabs and MUST be carefully reviewed and tested on all possible scenarios.
If this PR does not contain breaking changes please use different wording. Breaking changes are only MAJOR-grade changes.
| // The only direct "user tapped More" signal on the UITab path - no UITab delegate covers More. | ||
| // Mirrors the More branch of the legacy `shouldSelectViewController:`: enforce selection | ||
| // prevention on the More stack top before UIKit displays it. | ||
| if (self.tabs.count > 0 && [self isMoreNavigationControllerPresentInTabBar] && |
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What is the first part of the condition about: self.tabs.count > 0? Does it mean to check if we're using the UITab API?
If so -> I'd recommend we have it done differently. We should create a single decision point / source of truth of whether we rely on UITab or UIViewController based API, e.g. if ([self usesUITabApi]) and in every place were we need to decide whether the new API is in use or not - we should rely on value returned by that method.
If not -> I think then that you assume that availbility of iOS 26.1 implies usage of the new API -> then I'd like the @available(iOS 26.1, *) part to also be extracted into compile time macro, so the condition communicates clearly the intention behind it.
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this code was placed in a different method that ran for both paths, so this was a check for tab api, yes, but now this code is wrapped with availability check so here it's unneeded
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Okay, this change looks good then.
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I want also comment on the RNS_UITAB_API_AVAILABLE_XXX macro pair - I think we can do better.
Consider:
if (RNS_UITAB_API_ENABLED) {
// some code here
}I think it is superior -> no macro pair needed, clearly communicates that this is an if statement, you can even do else / else if branch if you need to. Right now you can't, right?
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one problem is the IDE
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I don't have these warnings present in my XCode - if I remove the if around the line with the warning you show - then I get one. Pod resintall + editor restart might help here.
| * With UITab-managed children (iOS >= 26.1) a replacement item does not repaint first time. | ||
| * Assigning a throwaway item first flips the internal logic so that the real assignment | ||
| * that follows paints synchronously. Remove once UIKit internals no longer require it. |
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I don't think I understand exactly what the problem was from this description.
What does it mean for the tab bar item to "repaint first time"?
You mean it's appearance configuration changes and that is not reflected on the screen?
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Screen.Recording.iPhone.18.Pro.25-09-2026.at.09.25.42.mp4
Reworded comment. This happens when changing systemItem at runtime. As I said in some other comment, I think having the test working + hot reload working is enough to keep this
3587014
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Okay, thanks for clarification. I'll leave this thread unresolved so it can be found more easily in the future. You might actually put this information in the PR description.
emitSelectionUpdate
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Hey, I've found a blocking problem, please see the video:
Screen.Recording.iPhone.17.28-09-2026.at.20.58.26.mp4
It seems that wrong navigation key is sent with state to the JS (and likely set in native). I think it happens because the key is read from selectedTab - this is not fine when more navigation controller is in play. I do not remember how it'd work beforehand, since I believe the self.selectedViewController pointed to moreNavigationController, but there surely was some logic responsible for handling this case present. We need to also handle it correctly.
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Requesting changes for the selection-flag lifetime issue on the UITab path (inline comment below).
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Remaining findings from another pass over the current head (1be84c9). The first four are behavioural on the UITab path (iOS 26.1+) and need checking on a device or simulator; the rest are cleanup.
| // update both. | ||
| if (![tabScreenCtrl.tabBarItem.title isEqualToString:newTitle] || ![tabScreenCtrl.title isEqualToString:newTitle]) { | ||
| tabScreenCtrl.title = newTitle; | ||
| tabScreenCtrl.tabBarItem.title = newTitle; |
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Runtime title changes never reach UITab.title, so iPad shows stale titles.
updateTabBarItemTitle:forTabScreenController: writes only controller.title and tabBarItem.title. tab.title is set once, in makeTabForTabScreenController:. Commit 3fdd70d ("source title for ipad") shows that iPad reads the title from the UITab itself, so:
- changing the
titleprop at runtime on iPad (iOS 26.1+) leaves the bar showing the title from when the tab was created; - a
systemItemtab with notitlegetstab.title = @""(the component view title is nil). The evaluated system title only lands on the item, so iPad shows an empty label.
The badge path already writes to both item and tab ("must land on both to render"). The title should do the same: set tabScreenCtrl.tab.title = newTitle under RNS_UITAB_API_ENABLED, including the evaluated system-item title.
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One more thing here I don't understand is why do we set both. Setting UITabBarItem.title should be enough, right? IIRC UIViewController.title is used only as a default in case the UITabBarItem.title is not set:
Documentation also gives important context here - the title MUST be initialized before the tabbaritem is added to the tab bar.
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actually needed to set also the tab.title 06ac680 for tabSidebar on iPad to work on first render
haven't verified the other claims, will do later
| didSelectTab:(UITab *)selectedTab | ||
| previousTab:(nullable UITab *)previousTab API_AVAILABLE(ios(18.0)) | ||
| { | ||
| if (!_isHandlingUserTabSelection) { |
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Implicit UIKit selection changes are no longer reconciled on the UITab path.
reconcileNavigationStateWithUIKitState exists for selection changes UIKit makes on its own. The documented case is More disappearing when an iPad app is resized to regular width. On the legacy path those changes go through the setSelectedViewController:/setSelectedIndex: overrides. On the UITab path:
- UIKit changes selection through
selectedTab, and there is nosetSelectedTab:override; - this callback returns early whenever
_isHandlingUserTabSelectionisNO, so an implicit change reported here is dropped.
Result: after the resize, _navigationState still names the More-hosted screen and JS never gets the Implicit update. Could you check this on iPad (iOS 26.1+) with a More-hosted tab selected? The early return here is the natural place to call reconciliation (guarded by !_isHandlingExplicitSelectionUpdate), or add a setSelectedTab: override that mirrors the existing ones.
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Not sure how do even handle this, but there must be some callback that allows us to handle this. We might react to resize / implicit change source etc., but we need to have that handled.
| // The only direct "user tapped More" signal on the UITab path - no UITab delegate covers More. | ||
| // Mirrors the More branch of the legacy `shouldSelectViewController:`: enforce selection | ||
| // prevention on the More stack top before UIKit displays it. | ||
| if ([self isMoreNavigationControllerPresentInTabBar] && item == self.moreNavigationController.tabBarItem) { |
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A repeated tap on More is no longer vetoed on the UITab path.
On the legacy path, re-tapping More goes through shouldSelectViewController: → interceptUserSelectionOfViewController:, which treats it as a repeat and returns NO. That blocks UIKit's native pop-to-root on the More stack. On the UITab path More gets no should-select callback, and tabBar:didSelectItem: fires after the fact, so it can't veto anything.
popToRootInMoreNavigationControllerRespectSelectionPrevention:YES only covers screens with preventNativeSelection. For any other More-hosted screen, re-tapping More pops back to the More list while _navigationState still names the hosted screen, and no event is emitted, so JS and the UI diverge. Can you check what happens there, and either restore the veto or emit the matching state update?
| for (RNSTabsScreenViewController *screenController in screenControllers) { | ||
| [tabs addObject:[self tabForTabScreenController:screenController]]; | ||
| } | ||
| self.tabs = tabs; |
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The animated argument is ignored on the UITab path.
The legacy branch honours animated via setViewControllers:animated:, but here self.tabs = tabs always installs without animation. The caller still computes animated:[self installedScreenControllers].count != 0, so the flag looks honoured when it isn't. Use [self setTabs:tabs animated:animated] (also iOS 18+) to keep behaviour consistent across paths.
| NSArray<RNSTabsScreenViewController *> *_Nullable _tabScreenControllers; | ||
|
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| /// Controllers currently installed in UIKit (see `installScreenControllers:animated:`). | ||
| /// On the UITab path (iOS 27+) `UITabBarController.viewControllers` is empty once `tabs` is set, |
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The UIKit configuration boundary is still leaky, and this doc comment is stale.
- This comment says "UITab path (iOS 27+)", but the gate is
@available(iOS 26.1, *). - On the UITab path, current-selection reads still bypass the boundary.
userDidSelectViewController:anduserDidRepeatViewControllerSelection:assert onself.selectedViewController, andevaluateOrientation,resolveCurrentContentScrollView,traitCollectionDidChange:andreconcileNavigationStateWithUIKitStateall readselectedViewController. MeanwhileupdateNavigationStateOnModelUpdateandisScreenControllerCurrentlySelected:readselectedTab. userDidRepeatSelectionOfTab:duplicatesuserDidRepeatViewControllerSelection:.
You confirmed that selectedTab and selectedViewController diverge while More is shown. That divergence is behind the More-related issues on this PR, and with two sources of truth chosen per call site it's hard to audit. I'd suggest a single selectedScreenController accessor in the boundary section, with More handled explicitly, used everywhere the current selection is read.
| #define RNS_IGNORE_SUPER_CALL_BEGIN \ | ||
| _Pragma("clang diagnostic push") \ | ||
| _Pragma("clang diagnostic ignored \"-Wobjc-missing-super-calls\"") | ||
| _Pragma("clang diagnostic push") _Pragma("clang diagnostic ignored \"-Wobjc-missing-super-calls\"") |
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nit: this reflow of RNS_IGNORE_SUPER_CALL_BEGIN, RNS_IPHONE_OS_VERSION_AVAILABLE and RNS_TABS_BOTTOM_ACCESSORY_AVAILABLE has no semantic change. It adds noise to an already large and risky diff, and to git blame on a shared header. Could you revert these hunks and keep only the UITab macro additions?
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wrong call from me, this makes more sense
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Yeah, seems right. Let's leave this formatting in this PR then.
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I tested both test-tabs-more-navigation-controller-ios and test-tabs-prevent-native-selection - it all seems to work fine - that's great!
I still have some remarks regarding the code - I'll open a PR to this one with my recommended changes.
| /// Controllers currently installed in UIKit (see `installScreenControllers:animated:`). | ||
| /// On the UITab path (iOS 26.1+) `UITabBarController.viewControllers` is empty once `tabs` is set, | ||
| /// so the installed set is tracked here; on the legacy path UIKit itself is the source of truth. | ||
| NSArray<RNSTabsScreenViewController *> *_Nullable _installedScreenControllers; |
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| /// Controllers currently installed in UIKit (see `installScreenControllers:animated:`). | |
| /// On the UITab path (iOS 26.1+) `UITabBarController.viewControllers` is empty once `tabs` is set, | |
| /// so the installed set is tracked here; on the legacy path UIKit itself is the source of truth. | |
| NSArray<RNSTabsScreenViewController *> *_Nullable _installedScreenControllers; | |
| /// Controllers currently installed in UIKit (see `installScreenControllers:animated:`). | |
| /// On the UITab path `UITabBarController.viewControllers` is empty once `tabs` is set, | |
| /// so the installed set is tracked here; on the legacy path UIKit itself is the source of truth. | |
| NSArray<RNSTabsScreenViewController *> *_Nullable _installedScreenControllers; |
avoid specifying the version explicitly here - doing so makes the comment much easier to go out of date. Especially, when this information is not important for understanding what the property is for.
| /// retains a hosted screen - the display outcome is version-dependent (iOS 26.x re-displays the | ||
| /// hosted screen, iOS 27 pops to the More list), so the `onMoreTabSelected` emit decision is | ||
| /// deferred to `willShowViewController:`, which reports what actually shows. | ||
| BOOL _pendingMoreTabSelectedEmit; |
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I think I know the code, but I don't understand this comment or it is misleading.
Screen.Recording.2026-09-30.at.12.13.08.mov
on iOS 27 it seems to work the same as on iOS 26 -> when you navigate to more tab, it shows the top controller of more navigation controller (the navigation controller state is preserved between tab switches).
Therefore I do no understand how "the display outcome is version-dependent. Let's describe the handled behaviour in detail if there is a difference indeed otherwise let's fix the comment.
If there is a difference - let's even add that difference description to the PR description.
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Not sure why the CI fails exactly. The failing test: Screen.Recording.2026-10-01.at.15.03.01.mov |
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Okay, in manual testing seems to work - the failing tests also seem to work when tested manually. I'm not entirely happy with the code - but proceeding here is a prio. We'll have time for style-refactors later down the road. Let's go. Thanks.
One thing - we need to make sure the a11y works - it is my suspicion - that's the reason behind CI failure here.
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Caution
This PR brings SIGNIFICANT change to tabs and MUST be carefully reviewed and tested on all possible scenarios.
Description
Migrates the children management of
RNSTabBarControllerfrom the legacyviewControllers-based API to the modernUITab-based API (UITabBarController.tabs/selectedTab) on iOS 26.1+. The legacy path remains in place for iOS < 26.1 and tvOS.UIKit ties newer tab-bar features to the
UITabAPI (e.g. the system search tab treatment,UISearchTab.automaticallyActivatesSearch), so adopting it is necessary.Note
UISearchTabis not adopted here — left for a followup PR. Thesearchsystem item gets a plainUITab. Behavioral consequence: on iOS 26.x the search tab still receives the system trailing-edge treatment, on iOS 27 it stays in place like any other tab until the followup lands.Changes
installScreenControllers:animated:,installedScreenControllers,selectedScreenController,applySelectedScreenController:— so the two mutually exclusive APIs meet in one place and the rest of the controller stays path-agnostic.installScreenControllers:builds thetabsarray, reusing existingUITabinstances by view-controller identity (a freshUITabfor a live, already-resolved VC is never built — UIKit's VC-ownership registry is keyed to the tab instance and crashes on replacement). TabidentifierisscreenKey.selectedTabis restored across re-sets, except while More is active (More has noUITab).tabBarController:shouldSelectTab:/didSelectTab:previousTab:mirroring the legacy delegate logic withshouldSelectViewController/didSelectViewController.UITabBarItemtabBarItemon aUITab-managed slot does not repaint the bar the first time (the slot is still bound to the bridged adoption-time item).createTabBarItemassigns a throwaway item immediatelybefore the real one — the first replacement flips the slot out of bridged mode, the second paints synchronously. Ugly, but the only item-level mechanism found that works; validated by e2e on 26.5 and 27.
UITabpath gets no tab-bar-controller delegate callback for More at all. The direct "user tapped More" signal isUITabBarDelegatetabBar:didSelectItem:(fires only for user taps)pushViewController:animated:interceptor on both paths; on push it flags the transition andnavigationController:willShowViewController:progresses navigationstate when the hosted tab shows (no other delegate reports it).
Known limitations
accessibilityIdentifieris not re-applied (pre-existing UIKit limitation — post-first-layout identifier writes never reach the buttons on either path; launch-time IDs work).Before & after - visual documentation
Nothing should change visually vs main branch, with one exception: on iOS 27 the
searchsystem item tab does not get the trailing-edge treatment (seeUISearchTabnote above).Test plan
Caution
This PR brings SIGNIFICANT change to tabs and MUST be carefully reviewed and tested on all possible scenarios.
Some of the important things to verify:
rendering of more controller, restoring correct previously selected tabs
showing and hiding more controller on iPad
selection prevention for regular tabs and more controller
runtime changes to styling, including icon updates
tab accessibility: tab ids and labels
Checklist