Game Center break Unity game orientation

I'm using Game Center to make leaderboard in game now, but i got a problem: even i set portrait orientation when build in Unity and Xcode, but when i login to Game Center, it change game's orientation to device's orientation. My game set in portrait, so when change to landscape orientation, it break the image and structure in game
I got the same problem when share Twitter, so anyone can fix it ?
Beside that, now i share Twitter with text and image, and it become a problem when i push Home button and back to game again: the screen became black (like when i share, but there is no share pop up and keyboard now). It became invisile (i can still touch to show, but it disapear in 1 seconds). I was okay with share before i push Home button and back to game.
Sorry for my English, please feed back for me soon

 

You can try this plugin to lock orientation to portrait (https://www.assetstore.unity3d.com/en/#!/content/57376)