Unity 2019 iOS build problem

Hi!Recently we started to upgrade our game from Unity 2017.2.1f1 to Unity 2019(Now we are using Unity 2019.1.8).We finally overcame the Android errors, but there are problems on iOS devices too.After building the game in Unity,we open it on XCode, and run it on our iOS device.While running on the device the XCode log seems normal(the game opens and initializes the services, etc), but the iOS device has black screen from the beggining.Any ideas on this?