iOS. Push notification from any app cause ue4 game freeze
How to reproduce:
- Build and run any UE4 (4.22 or 4.23) project on iOS 13
- Receive a notification during the game. Render thread will freeze
What will happen:
Receive a notification during the game developed on UE4. Render thread will freeze for a couple of seconds but the audio thread will work fine.
This leads to an out of sync image and sound, which is very bad for music games and critical for shooters!
Muted device doesn’t freeze by notifications (watch the video below)
This is a critical problem for us and our team began to search where else you can find the same bug.
And we found …
This is reproducible in any (??) UE4 project running at least on iOS 13. For example:
Appstore: FORTNITE, Oceanhorn 2, Action RPG, UnrealMatch3
Marketplace (after build): Action RPG, UnrealMatch3, FaceAR Sample
We recorded a video with UE4 games on two different devices running on iOS 13. [UE4 Development] Push notification from any app cause UE4 game freezing on iOS 13 - YouTube
Look at screenshot from UE4 profiler from iOS device. Each peak on the chart is the moment when a notification was displayed.
How can we fix this?