[nits] refactor code for reuse

* Refactor and reuse `setNewInternalUser` and `createDefaultPushSubscription` in `createUserFromLegacyPlayer`

* Make a helper method `isCurrentUser` to wrap checking if a user is the current one.

Author: nan-li

iOS_SDK/OneSignalSDK/OneSignalUser/Source/OSUserRequests.swift

@@ -320,7 +320,7 @@ class OSUserExecutor {
                 // 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
                 // Fetch the user only if its the current user
-                if let _ = OneSignalUserManagerImpl.sharedInstance.identityModelStore.getModel(modelId: request.identityModel.modelId),
+                if OneSignalUserManagerImpl.sharedInstance.isCurrentUser(request.identityModel),
                    let identity = request.parameters?["identity"] as? [String: String],
                    let externalId = identity[OS_EXTERNAL_ID] {
                     fetchUser(aliasLabel: OS_EXTERNAL_ID, aliasId: externalId, identityModel: request.identityModel)
@@ -368,7 +368,7 @@ class OSUserExecutor {
                 request.identityModel.hydrate(identityObject)
 
                 // Fetch this user's data if it is the current user
-                guard OneSignalUserManagerImpl.sharedInstance.identityModelStore.getModel(modelId: request.identityModel.modelId) != nil
+                guard OneSignalUserManagerImpl.sharedInstance.isCurrentUser(request.identityModel)
                 else {
                     executePendingRequests()
                     return
@@ -421,7 +421,7 @@ class OSUserExecutor {
 
             // the anonymous user has been identified, still need to Fetch User as we cleared local data
             // Fetch the user only if its the current user
-            if let _ = OneSignalUserManagerImpl.sharedInstance.identityModelStore.getModel(modelId: request.identityModelToUpdate.modelId) {
+            if OneSignalUserManagerImpl.sharedInstance.isCurrentUser(request.identityModelToUpdate) {
                 fetchUser(aliasLabel: OS_EXTERNAL_ID, aliasId: request.aliasId, identityModel: request.identityModelToUpdate)
             } else {
                 executePendingRequests()
@@ -435,7 +435,7 @@ class OSUserExecutor {
 
                     removeFromQueue(request)
                     // Fetch the user only if its the current user
-                    if let _ = OneSignalUserManagerImpl.sharedInstance.identityModelStore.getModel(modelId: request.identityModelToUpdate.modelId) {
+                    if OneSignalUserManagerImpl.sharedInstance.isCurrentUser(request.identityModelToUpdate) {
                         fetchUser(aliasLabel: OS_EXTERNAL_ID, aliasId: request.aliasId, identityModel: request.identityModelToUpdate)
                         // TODO: Link ^ to the new user... what was this todo for?
                     }

iOS_SDK/OneSignalSDK/OneSignalUser/Source/OneSignalUserManagerImpl.swift

@@ -248,32 +248,12 @@ public class OneSignalUserManagerImpl: NSObject, OneSignalUserManager {
      */
     private func createUserFromLegacyPlayer(_ playerId: String) {
         // 1. Create the Push Subscription Model
-        let sharedUserDefaults = OneSignalUserDefaults.initShared()
-        let reachable = OSNotificationsManager.currentPermissionState.reachable
-        let pushToken = sharedUserDefaults.getSavedString(forKey: OSUD_PUSH_TOKEN, defaultValue: nil)
-        let pushSubscriptionModel = OSSubscriptionModel(
-            type: .push,
-            address: pushToken,
-            subscriptionId: playerId,
-            reachable: reachable,
-            isDisabled: false, // TODO: Get from cache or something if there?
-            changeNotifier: OSEventProducer())
-        
-        // 2. Add pushSubscription to store
-        pushSubscriptionModelStore.add(id: OS_PUSH_SUBSCRIPTION_MODEL_KEY, model: pushSubscriptionModel, hydrating: false)
-        
-        // 3. Set the internal user
-
-        let identityModel = OSIdentityModel(aliases: nil, changeNotifier: OSEventProducer())
-        self.identityModelStore.add(id: OS_IDENTITY_MODEL_KEY, model: identityModel, hydrating: false)
+        let pushSubscriptionModel = createDefaultPushSubscription(subscriptionId: playerId)
 
-        let propertiesModel = OSPropertiesModel(changeNotifier: OSEventProducer())
-        self.propertiesModelStore.add(id: OS_PROPERTIES_MODEL_KEY, model: propertiesModel, hydrating: false)
+        // 2. Set the internal user
+        let newUser = setNewInternalUser(externalId: nil, pushSubscriptionModel: pushSubscriptionModel)
 
-        let newUser = OSUserInternalImpl(identityModel: identityModel, propertiesModel: propertiesModel, pushSubscriptionModel: pushSubscriptionModel)
-        _user = newUser
-
-        // 4. Do the request
+        // 3. Make the request
         OSUserExecutor.fetchIdentityBySubscription(newUser)
     }
 
@@ -331,6 +311,13 @@ public class OneSignalUserManagerImpl: NSObject, OneSignalUserManager {
         )
     }
 
+    /**
+     Returns if the OSIdentityModel passed in belongs to the current user. This method is used in deciding whether or not to hydrate via a server response, for example.
+     */
+    func isCurrentUser(_ identityModel: OSIdentityModel) -> Bool {
+        return self.identityModelStore.getModel(modelId: identityModel.modelId) != nil
+    }
+    
     /**
      Clears the existing user's data in preparation for hydration via a fetch user call.
      */
@@ -420,7 +407,7 @@ public class OneSignalUserManagerImpl: NSObject, OneSignalUserManager {
 
         // TODO: We will have to save subscription_id and push_token to user defaults when we get them
 
-        let pushSubscription = pushSubscriptionModel ?? createDefaultPushSubscription()
+        let pushSubscription = pushSubscriptionModel ?? createDefaultPushSubscription(subscriptionId: nil)
 
         // Add pushSubscription to store if not present
         if !pushSubscriptionModelStore.getModels().keys.contains(OS_PUSH_SUBSCRIPTION_MODEL_KEY) {
@@ -431,11 +418,14 @@ public class OneSignalUserManagerImpl: NSObject, OneSignalUserManager {
         return self.user
     }
 
-    func createDefaultPushSubscription() -> OSSubscriptionModel {
+    /**
+     Creates a default Push Subscription Model using the optionally passed in subscriptionId. An scenario where the subscriptionId will be passed in is when we are converting a legacy player's information from 3.x  into a Push Subscription Model.
+     */
+    func createDefaultPushSubscription(subscriptionId: String?) -> OSSubscriptionModel {
         let sharedUserDefaults = OneSignalUserDefaults.initShared()
         let reachable = OSNotificationsManager.currentPermissionState.reachable
         let token = sharedUserDefaults.getSavedString(forKey: OSUD_PUSH_TOKEN, defaultValue: nil)
-        let subscriptionId = sharedUserDefaults.getSavedString(forKey: OSUD_PUSH_SUBSCRIPTION_ID, defaultValue: nil)
+        let subscriptionId = subscriptionId ?? sharedUserDefaults.getSavedString(forKey: OSUD_PUSH_SUBSCRIPTION_ID, defaultValue: nil)
 
         return OSSubscriptionModel(type: .push,
                                    address: token,