title: Swift - How sending a post notification from OneSignal SDK to specific username tag?
body: <p>How Can I send a post notification to specific tag like (username: "@john") from Swift/iOS Native SDK. I have sendTag OneSignal before. I'm sending below a user with playerID. But It's not enough. Someone can login with different accounts. So same playerID will be for all of them. When I add tag line it doesn't work as I expect. How to work Player ID &amp;&amp; username tag together.</p>
  
  <pre><code>OneSignal.sendTag("username", value: "\(username)")
  </code></pre>
  
  <p>If someone explain this, It would be great.</p>
  
  <pre><code>DataService.ds.REF_USERS.child(userUUID).child("playerID").observeSingleEvent(of: .value, with: { snapshot in
  
  if let playerID = snapshot.value as? String {
  
      OneSignal.idsAvailable({ (userId, pushToken) in
          print("UserId:%@", userId ?? "")
  
          self.showErrorAlert("Player ID Here:", msg: "\(userId!)")
  
          if (pushToken != nil) {
  
              OneSignal.postNotification(["contents": ["en": "@username wrote a comment: \(trimmed)"],
                                          "include_player_ids": [playerID],
                                          "send_after": "2017-01-10 20:10:00 GMT+0300",
                                          "tag": ["field": "tag", "key": "username", "relation": "=", "value": "john",
                  ])
          }
  
      })
  
  } 
  })
  </code></pre>