[nits] update comments for create user response

* Also update some comments for addressing the Create User response

Author: nan-li

iOS_SDK/OneSignalSDK/OneSignalUser/Source/OSUserRequests.swift

@@ -167,13 +167,14 @@ class OSUserExecutor {
             return
         }
         OneSignalClient.shared().execute(request) { response in
-            // TODO: Differentiate if we need to fetch based on response code 200, 201, 202
-            // Create User's response won't send us the user's complete info if this user already existed.
-            // We can parse the response OR fetch user (and then parse response then)
-            // For now, do both, as we should parse to get the subscription_id from this request
+            // TODO: Differentiate if we need to fetch the user based on response code of 200, 201, 202
+            // Create User's response won't send us the user's complete info if this user already exists
             if let response = response {
+                // Parse the response for any data we need to update
                 parseFetchUserResponse(response: response, identityModel: request.identityModel, originalPushToken: originalPushToken)
-                // If we logged into an external_id, fetch the user data
+
+                // If this user already exists and we logged into an external_id, fetch the user data
+                // TODO: Only do this if response code is 200 or 202
                 if let identity = request.parameters?["identity"] as? [String: String],
                    let externalId = identity[OS_EXTERNAL_ID] {
                     fetchUser(aliasLabel: OS_EXTERNAL_ID, aliasId: externalId, identityModel: request.identityModel)