Added .description so onAdEvent returns a string (#119)

Co-authored-by: edougher <[email protected]>

Author: edougher

ios/RNJWPlayer/RNJWPlayerView.swift

@@ -1384,7 +1384,7 @@ class RNJWPlayerView : UIView, JWPlayerDelegate, JWPlayerStateDelegate, JWAdDele
     // MARK: - JWPlayer Ad Delegate
 
     func jwplayer(_ player:JWPlayer, adEvent event:JWAdEvent) {
-        self.onAdEvent?(["client": event.client, "type": event.type])
+        self.onAdEvent?(["client": event.client.description, "type": event.type.description])
     }
 
     // MARK: - JWPlayer AV Delegate

ios/RNJWPlayer/RNJWPlayerViewController.swift

@@ -486,7 +486,7 @@ class RNJWPlayerViewController : JWPlayerViewController, JWPlayerViewControllerD
 
     override func jwplayer(_ player: JWPlayer, adEvent event: JWAdEvent) {
         super.jwplayer(player, adEvent:event)
-        parentView?.onAdEvent?(["client": event.client, "type": event.type])
+        parentView?.onAdEvent?(["client": event.client.description, "type": event.type.description])
     }
 
     // MARK: - JWPlayer Cast Delegate