title: Send tag to OneSignal after log in
body: <p>I want to send tag to a specific user after he/she logged in so he/she can receive notifications. Only logged in users will receive notifications. 
  When he/she logs out, I will delete his/her tag.
  How can I do this?</p>
  
  <p>My code in AppDelegate:</p>
  
  <pre><code>let oneSignal: OneSignal = OneSignal(launchOptions: launchOptions, appId: "&lt;my-app-id&gt;") {
          (message, additionalData, isActive) in
  
          if (additionalData != nil) {
              NSLog("APP LOG ADDITIONALDATA: %@", additionalData);
              let displayMessage: NSString = NSString(format:"NotificationMessage:%@", message);
  
              var messageTitle: NSString = "";
              if (additionalData["discount"] != nil) {
                  messageTitle = additionalData["discount"] as String
              }
              else if (additionalData["bonusCredits"] != nil) {
                  messageTitle = additionalData["bonusCredits"] as String;
              }
              else if (additionalData["actionSelected"] != nil) {
                  messageTitle = NSString(format:"Pressed ButtonId:%@", additionalData["actionSelected"] as String);
              }
  
              var alertView: UIAlertView = UIAlertView(title: messageTitle,
                  message:displayMessage,
                  delegate:self,
                  cancelButtonTitle:"Close");
  
              alertView.show();
          }
  
          else if (isActive) {
              var alertView: UIAlertView = UIAlertView(title:"OneSignal Message",
                  message:message,
                  delegate:self,
                  cancelButtonTitle:"Close");
              alertView.show();
          }
      }
  </code></pre>
  
  <p>My code in my LogInViewController:</p>
  
  <pre><code>let oneSignal = OneSignal()
  oneSignal.sendTag("username", value: self.usernameTextField.text)
  </code></pre>
  
  <p>The code in my appDelegate is working fine, my users already receive notifications. But they can receive notifications even if they're not logged in.</p>