即使“优先级”设置为高，APP强制退出时iOS上的GCM也不会收到推送通知

I'm using GCM example app for iOS from google. So far the app works when the app is on the foreground and background i.e. it receive a message I sent using postman. But when I force the app to quit, it doesn't receive my message anymore. I do set "priority" parameters to high as suggested by virtually everyone, but the app is still doesn't receive any message after force quit.I'm using GCM example app for iOS from google.