Issue with crashes on iOS 18

[evandorn]

We recently upgraded our testing devices from iOS 16 to iOS 18. We are getting tons of random crashes from what appears to be KIF interacting with a UIButton or some UI element. In all of the traces we see KIF as the last calls from our app and then further down in KIF library we see UIKit code called and it crashes with a segmentation fault from [UIImageSymbolConfiguration _initWithTraitCollection:]. We've also tried reproducing it locally and we've been unable to get this to happen from a local KIF test run. We're seeing these traces from test runs on AWS Device Farm using iPad on iOS 18. We're using Xcode 26.0.1 and we are running KIF 3.12.3. Is there a known issue with KIF and iOS18? We have observed that if we test on iOS26 we do not get these crashes. Any help is appreciated!

052159d2-393a-4ba5-98de-8e45d4b371de.log

[justinseanmartin]

From what I see of KIF on this call stack, it is just spinning the runloop waiting until the app to idle (e.g. animations) after performing the tap action. I haven't seen anything like this personally. I'll give you the AI analysis in case that helps. The TL;DR is likely a race condition in the App's interaction with UIKit.

My suggestions from reading the AI analysis would be to start with a hack to see if adding some explicit waits or tweaking the KIF configurable wait times before tapping menu items helps (potentially not a good fix, but an interesting data point). You could also try a different minor version of iOS 18 (is there a reason you're choosing 18.3.2 in particular?) or see if the same issues exist on iOS 26. You could also try enabling guard malloc and seeing if it crashes earlier pointing to where the deallocated trait collection is coming from.

AI Analysis

Root Cause

The crash appears to be a UIKit bug in iOS 18, not a bug in KIF. It occurs during layout of navigation bar button items while a view controller transition is in progress:

1. View controller transition – UITransitionView transition:fromView:toView: (push/pop)
2. Navigation bar layout – _UINavigationBarContentView layoutSubviews
3. Button bar layout – _UIButtonBarItemLayout, minimumLayoutWidthGivenMinimumSpaceWidth:
4. UIButton baseline layout – viewForLastBaselineLayout → _imageForState:applyingConfiguration:
5. Crash – [UIImageSymbolConfiguration _initWithTraitCollection:] → objc_release (segfault)

UIKit is trying to create an UIImageSymbolConfiguration from a trait collection during layout. The crash in objc_release suggests the trait collection is invalid or already deallocated (use-after-free/over-release). This fits with changes in how UIKit manages trait collections during transitions on iOS 18.

Why iOS 18?

Similar crashes have been reported on Apple Developer Forums:

• Crashes in _UIGetCurrentFallbackTraitCollection with memory issues
• Crashes in _UIButtonBarItemLayout when reusing UIBarButtonItem/UIButton across view controllers – creating new instances per view controller avoids the crash
• Another workaround: disabling animations in view controller transitions (e.g., in splitViewController(_:collapseSecondary:onto:))

This points to an iOS 18 UIKit regression around navigation bar button layout and trait collection handling during transitions.

Why AWS Device Farm / iPad?

1. Timing – Different or slower run loop timing on cloud devices can make race conditions more likely
2. iPad layout – iPad navigation bar layout (e.g., split view) uses different code paths
3. SF Symbols – Navigation bar buttons often use SF Symbols, which depend on UIImageSymbolConfiguration and trait collections

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Recommendations

1. In the App Under Test (Primary Fix)

• Avoid reusing UIBarButtonItem/UIButton across view controllers – create new instances per view controller
• If you animate view controller changes, try disabling or simplifying those transitions where possible

2. In Tests

• Increase animation and stabilization timeouts before interacting with views that cause navigation:

[[tester usingAnimationWaitingTimeout:5.0]
usingAnimationStabilizationTimeout:1.0]
usingMainThreadDispatchStabilizationTimeout:1.0];

• Or add a short delay after taps that trigger navigation transitions
• Consider slowing down taps on navigation bar items so layout has more time to settle

3. KIF Configuration

KIF’s default timeouts are animationWaitingTimeout: 2.0, animationStabilizationTimeout: 0.5, and mainThreadDispatchStabilizationTimeout: 0.5. waitForAnimationsToFinish checks for _UIParallaxDimmingView as an indicator of in-progress transitions, but on iOS 18 this heuristic may be insufficient.

4. Report the issue to Apple

If you’re willing to file a Feedback report to Apple, this analysis and the crash stack could be added as context.