Hello everyone,
ARKit XR Plugin is causing app to crash on iOS 11.0 in 100%, because it is using newer API that was introduced in later versions of iOS. This is reproducible in our released app and in AR Foundation samples.
How to reproduce:
- download AR Foundation samples - GitHub - Unity-Technologies/arfoundation-samples at 2.1
- build SimpleAR scene for iOS using Xcode 11 (no changes to the sample is needed), the resulted project will be targeting iOS 11.0
- build and deploy resulted Xcode project on a real device running iOS 11.0, using Xcode 11
- terminate the app in app switcher, ([UnityAppController -applicationWillTerminate] will be called, etc)
The app will crash with the following message in the Xcode console:
2019-09-23 20:13:09.119948+0300 samples[1161:3786176] -[ARWorldTrackingConfiguration setDetectionImages:]: unrecognized selector sent to instance 0x1c0097480
2019-09-23 20:13:09.271182+0300 samples[1161:3786176] Uncaught exception: NSInvalidArgumentException: -[ARWorldTrackingConfiguration setDetectionImages:]: unrecognized selector sent to instance 0x1c0097480
(
0 CoreFoundation 0x0000000182033d50 + 148
1 libobjc.A.dylib 0x0000000181548528 objc_exception_throw + 56
2 CoreFoundation 0x00000001820411f8 + 0
3 CoreFoundation 0x00000001820396e4 + 1380
4 CoreFoundation 0x0000000181f1f0dc _CF_forwarding_prep_0 + 92
5 samples 0x000000010623385c _ZN21ImageTrackingProvider4StopEv + 284
6 samples 0x00000001062339b8 _ZN21ImageTrackingProvider9OnDestroyEv + 20
7 samples 0x000000010623437c _ZN21ImageTrackingProviderD2Ev + 20
8 libsystem_c.dylib 0x0000000181abdbd8 __cxa_finalize_ranges + 384
9 libsystem_c.dylib 0x0000000181a670c0 exit + 24
10 UIKit 0x000000018b4cacf4 + 0
11 UIKit 0x000000018b939b04 + 344
12 UIKit 0x000000018b6b3680 + 292
13 UIKit 0x000000018b6a6b24 + 288
14 UIKit 0x000000018b435808 + 132
15 CoreFoundation 0x0000000181fdb8b8 + 32
16 CoreFoundation 0x0000000181fd9270 + 412
17 CoreFoundation 0x0000000181fd982c + 1292
18 CoreFoundation 0x0000000181efa2d8 CFRunLoopRunSpecific + 436
19 GraphicsServices 0x0000000183d8bf84 GSEventRunModal + 100
20 UIKit 0x000000018b4a6880 UIApplicationMain + 208
21 samples 0x0000000104f17540 main + 208
22 libdyld.dylib 0x0000000181a1e56c + 4
)
2019-09-23 20:13:09.275515+0300 samples[1161:3786176] *** Terminating app due to uncaught exception ‘NSInvalidArgumentException’, reason: ‘-[ARWorldTrackingConfiguration setDetectionImages:]: unrecognized selector sent to instance 0x1c0097480’
The most important line here is -[ARWorldTrackingConfiguration setDetectionImages:]: unrecognized selector sent to instance 0x1c0097480. Apparently, an instance of ImageTrackingProvider is trying to unset the detection images in its destructor. I’m not sure why ARKit XR/AR Foundation is trying to (un-)set detection images in SimpleAR scene (as it doesn’t use this functionality), but I’m definitely sure that it should not try to use this API on the iOS version where it is not available. Detection images property was introduced in iOS 11.3 - detectionImages | Apple Developer Documentation. We don’t use detection images in our app as well.
Looks like this code is called during app termination process, so users don’t see it, thus it is not as severe as usual 100% crash, but it floods the crash reports, making it harder to find our own app’s crashes.
Prerequisites:
- Xcode 11.0 (11A420a)
- Unity 2019.2.3.f1
- ARKit XR Plugin 2.2.0 preview 5 (we are also getting this crash on 2.1.0 version released in AppStore)
- AR Foundation 2.2.0 preview 3
Expected behavior: the app doesn’t crash on iOS 11.0
Actual behavior: the app crashes on iOS 11.0