diff --git a/cocos/platform/ios/CCDevice.mm b/cocos/platform/ios/CCDevice.mm
index 3a72be780a..5eeaf7ccaa 100644
--- a/cocos/platform/ios/CCDevice.mm
+++ b/cocos/platform/ios/CCDevice.mm
@@ -128,6 +128,8 @@ static CCAccelerometerDispatcher* s_pAccelerometerDispatcher;
             
         case UIInterfaceOrientationPortrait:
             break;
+        default:
+            NSAssert(false, @"unknow orientation");
     }
 
     cocos2d::EventAcceleration event(*_acceleration);