title: Firebase messaging notification message vs data message and different behavior on ios/android
body: <p>When i send a notification message, under android i can not set the largeIcon, so i must use data message and construct myself the notification inside the notification service who listen incoming data message.</p>
  
  <p>However, on IOS, their is no such "notification service" running in background and the app will receive the data message only when it's become foreground (as far as i understand). so it's seam on ios the only choice i have is to send notification message with are incompatible with android</p>
  
  <p>Is their something i miss ?</p>