Crash (EXC_BREAKPOINT) in DeviceAccessManager.advertisingIdentifier() when ASIdentifierManager returns nil

[jstamatova]

Describe the bug

DeviceAccessManager.advertisingIdentifier() force-bridges ASIdentifierManager.shared().advertisingIdentifier into a non-optional Swift UUID:

// PrebidMobile/Swift/PrebidMobileRendering/Utilities/DeviceAccessManager.swift:85
@objc public func advertisingIdentifier() -> String {
    ASIdentifierManager.shared().advertisingIdentifier.uuidString
}

Apple annotates -[ASIdentifierManager advertisingIdentifier] as nonnull, so it bridges to a non-optional UUID in Swift. But in rare device states the ObjC property returns nil (the identifier is fetched over XPC from a system daemon that can be unavailable — e.g. very early in launch before the AdSupport service is ready, just after boot / before first unlock, under memory pressure / XPC failure, or under certain MDM / Screen Time restrictions). When it returns nil, the implicit NSUUID? -> UUID bridge calls UUID._unconditionallyBridgeFromObjectiveC, which traps -> EXC_BREAKPOINT and the app crashes.

Note: normal ATT denial / notDetermined does NOT cause this — that returns the all-zeros UUID (00000000-0000-0000-0000-000000000000), which bridges fine. The crash is specifically the nil case, where the OS returns nil despite the nonnull annotation.

This is hit whenever a bid request is built with Targeting.shared.isAllowedAccessDeviceData == true (PBMDeviceInfoParameterBuilder.m:88 reads deviceAccessManager.advertisingIdentifier), so any fetchDemand() call can crash.

To Reproduce
Steps to reproduce the behavior:

1. Force ASIdentifierManager.shared().advertisingIdentifier to return nil (e.g. swizzle the getter for testing).
2. Ensure Targeting.shared.isAllowedAccessDeviceData returns true.
3. Trigger a bid request via BannerAdUnit.fetchDemand(...).
4. See error - app crashes with EXC_BREAKPOINT in DeviceAccessManager.advertisingIdentifier() at DeviceAccessManager.swift:85.

Expected behavior

The SDK should tolerate a nil advertising identifier (fall back to an empty string / omit the ifa param) instead of trapping. Suggested fix - treat the value as optional:

@objc public func advertisingIdentifier() -> String {
    ASIdentifierManager.shared().advertisingIdentifier?.uuidString ?? ""
}

Screenshots

Symbolicated crash stack (abridged):

Crashed: com.apple.main-thread
0  Foundation      UUID._unconditionallyBridgeFromObjectiveC + 196
1  PrebidMobile    DeviceAccessManager.advertisingIdentifier()  (DeviceAccessManager.swift:85)
2  PrebidMobile    -[PBMDeviceInfoParameterBuilder buildBidRequest:]  (PBMDeviceInfoParameterBuilder.m:88)
3  PrebidMobile    +[PBMParameterBuilderService buildParamsDictWithAdConfiguration:...]
5  PrebidMobile    -[PBMBidRequester_Objc getRTBRequest]  (PBMBidRequester.m:180)
6  PrebidMobile    -[PBMBidRequester_Objc makeRequestWithCompletion:]  (PBMBidRequester.m:75)
9  PrebidMobile    UserAgentService.fetchUserAgent(completion:)  (UserAgentService.swift:37)
11 PrebidMobile    -[PBMBidRequester_Objc requestBidsWithCompletion:]  (PBMBidRequester.m:55)
12 PrebidMobile    AdUnit.baseFetchDemand(adObject:completion:)  (AdUnit.swift:182)
13 PrebidMobile    AdUnit.fetchDemand(completionBidInfo:)  (AdUnit.swift:113)
14 <app>           BannerAdUnit.fetchDemand { ... }

Desktop (please complete the following information):

• OS: N/A (iOS SDK issue, not desktop)
• Browser: N/A
• Version: N/A

Smartphone (please complete the following information):

• Device: Multiple (47 distinct devices affected in production)
• OS: iOS (observed on iOS 18.7)
• Browser: N/A (native app, in-app ad rendering)
• Version: PrebidMobile 3.3.1 (same unguarded code also present on master)

Additional context

Low but persistent volume in our production Crashlytics - 50 occurrences across 47 devices (0.6% of crashing users). The root cause is entirely inside the SDK: apps cannot prevent ASIdentifierManager from returning nil (it comes from a system daemon being momentarily unavailable), so this can only be fixed upstream by making the bridge nil-safe.