Game Center Issue

https://www.raywenderlich.com/60980/game-center-tutorial-how-to-make-a-simple-multiplayer-game-with-sprite-kit-part-1

Hi, guys.
this is the link what i’m looking now.
The final project is working well in my iPhone4s.
But it is crashed in my iPhone6.
After match finished, and when i moved in iPhone4s, then the game what is in the iPhone6 has crashed.
If anyone know about it, please help me.
Best regards.