title: How to send a notification with a category using Firebase
body: <p>I'm implementing an interactive remote notification in iOS. I'm sending notifications via Firebase. The notification should contain a "category" identifier to be associated with a concrete action. An example from a tutorial:</p>
  
  <p>{    aps : { 
          alert : "notificationText",
          category: "myCategory"
     } 
  }</p>
  
  <p>But how to use this JSON and assign a category for a notification in Firebase?</p>