Make more no-ops if there is no user instance

*Calling the `user` property of the `OneSignalUserManagerImpl` will return a mock user, the user instance, or call start().
* In some methods, if there is no user instance, don't trigger a start() call, to prevent deadlocks if these methods are called by start() itself.
* Currently, only the properties model and subscription model may have update enqueued at the end of the start() method to enqueue any changes such as timezone and app version for the user instance, which exists by this point.
* The other refactors are for safety.

Author: nan-li

iOS_SDK/OneSignalSDK/OneSignalUser/Source/Executors/OSUserExecutor.swift

@@ -119,8 +119,9 @@ class OSUserExecutor {
 
             // Translate the last request into a Create User request, if the current user is the same
             if let request = transferSubscriptionRequestQueue.last,
+               let userInstance = OneSignalUserManagerImpl.sharedInstance._user,
                OneSignalUserManagerImpl.sharedInstance.isCurrentUser(request.aliasId) {
-                createUser(OneSignalUserManagerImpl.sharedInstance.user)
+                createUser(userInstance)
             }
         }
     }
@@ -396,9 +397,10 @@ extension OSUserExecutor {
 
                 self.removeFromQueue(request)
 
-                if OneSignalUserManagerImpl.sharedInstance.isCurrentUser(request.identityModelToUpdate) {
+                if let userInstance = OneSignalUserManagerImpl.sharedInstance._user,
+                    OneSignalUserManagerImpl.sharedInstance.isCurrentUser(request.identityModelToUpdate) {
                     // Generate a Create User request, if it's still the current user
-                    self.createUser(OneSignalUserManagerImpl.sharedInstance.user)
+                    self.createUser(userInstance)
                 } else {
                     // This will hydrate the OneSignal ID for any pending requests
                     self.createUser(aliasLabel: request.aliasLabel, aliasId: request.aliasId, identityModel: request.identityModelToUpdate)
@@ -544,7 +546,7 @@ extension OSUserExecutor {
         }
 
         if let propertiesObject = parsePropertiesObjectResponse(response) {
-            OneSignalUserManagerImpl.sharedInstance.user.propertiesModel.hydrate(propertiesObject)
+            OneSignalUserManagerImpl.sharedInstance._user?.propertiesModel.hydrate(propertiesObject)
         }
 
         // Now parse email and sms subscriptions

iOS_SDK/OneSignalSDK/OneSignalUser/Source/OSPropertiesModelStoreListener.swift

@@ -45,14 +45,15 @@ class OSPropertiesModelStoreListener: OSModelStoreListener {
     }
 
     func getUpdateModelDelta(_ args: OSModelChangedArgs) -> OSDelta? {
-        guard let _ = OSPropertiesSupportedProperty(rawValue: args.property) else {
-            OneSignalLog.onesignalLog(.LL_ERROR, message: "OSPropertiesModelStoreListener.getUpdateModelDelta encountered unsupported property: \(args.property)")
+        guard let _ = OSPropertiesSupportedProperty(rawValue: args.property),
+              let userInstance = OneSignalUserManagerImpl.sharedInstance._user
+        else {
+            OneSignalLog.onesignalLog(.LL_ERROR, message: "OSPropertiesModelStoreListener.getUpdateModelDelta encountered unsupported property: \(args.property) or no user instance")
             return nil
         }
-
         return OSDelta(
             name: OS_UPDATE_PROPERTIES_DELTA,
-            identityModelId: OneSignalUserManagerImpl.sharedInstance.user.identityModel.modelId,
+            identityModelId: userInstance.identityModel.modelId,
             model: args.model,
             property: args.property,
             value: args.newValue

iOS_SDK/OneSignalSDK/OneSignalUser/Source/OSSubscriptionModelStoreListener.swift

@@ -37,9 +37,13 @@ class OSSubscriptionModelStoreListener: OSModelStoreListener {
     }
 
     func getAddModelDelta(_ model: OSSubscriptionModel) -> OSDelta? {
+        guard let userInstance = OneSignalUserManagerImpl.sharedInstance._user else {
+            OneSignalLog.onesignalLog(.LL_ERROR, message: "OSSubscriptionModelStoreListener.getAddModelDelta has no user instance")
+            return nil
+        }
         return OSDelta(
             name: OS_ADD_SUBSCRIPTION_DELTA,
-            identityModelId: OneSignalUserManagerImpl.sharedInstance.user.identityModel.modelId,
+            identityModelId: userInstance.identityModel.modelId,
             model: model,
             property: model.type.rawValue, // push, email, sms
             value: model.address ?? ""
@@ -50,9 +54,13 @@ class OSSubscriptionModelStoreListener: OSModelStoreListener {
      The `property` and `value` is not needed for a remove operation, so just pass in some model data as placeholders.
      */
     func getRemoveModelDelta(_ model: OSSubscriptionModel) -> OSDelta? {
+        guard let userInstance = OneSignalUserManagerImpl.sharedInstance._user else {
+            OneSignalLog.onesignalLog(.LL_ERROR, message: "OSSubscriptionModelStoreListener.getRemoveModelDelta has no user instance")
+            return nil
+        }
         return OSDelta(
             name: OS_REMOVE_SUBSCRIPTION_DELTA,
-            identityModelId: OneSignalUserManagerImpl.sharedInstance.user.identityModel.modelId,
+            identityModelId: userInstance.identityModel.modelId,
             model: model,
             property: model.type.rawValue, // push, email, sms
             value: model.address ?? ""
@@ -66,14 +74,18 @@ class OSSubscriptionModelStoreListener: OSModelStoreListener {
         // The user update call increases the session_count while the subscription update would update
         // something like the app_version. If the app_version hasn't changed since the last session, there
         // wouldn't be an update needed (among other system-level properties).
-        if let onesignalId = OneSignalUserManagerImpl.sharedInstance.user.identityModel.onesignalId {
+        guard let userInstance = OneSignalUserManagerImpl.sharedInstance._user else {
+            OneSignalLog.onesignalLog(.LL_ERROR, message: "OSSubscriptionModelStoreListener.getUpdateModelDelta has no user instance")
+            return nil
+        }
+        if let onesignalId = userInstance.identityModel.onesignalId {
             let condition = OSIamFetchReadyCondition.sharedInstance(withId: onesignalId)
             condition.setSubscriptionUpdatePending(value: true)
         }
 
         return OSDelta(
             name: OS_UPDATE_SUBSCRIPTION_DELTA,
-            identityModelId: OneSignalUserManagerImpl.sharedInstance.user.identityModel.modelId,
+            identityModelId: userInstance.identityModel.modelId,
             model: args.model,
             property: args.property,
             value: args.newValue

iOS_SDK/OneSignalSDK/OneSignalUser/Source/OneSignalUserManagerImpl.swift

@@ -384,12 +384,12 @@ public class OneSignalUserManagerImpl: NSObject, OneSignalUserManager {
     }
 
     func isCurrentUser(_ externalId: String) -> Bool {
-        guard !externalId.isEmpty else {
-            OneSignalLog.onesignalLog(.LL_ERROR, message: "isCurrentUser called with empty externalId")
+        guard let userInstance = _user, !externalId.isEmpty else {
+            OneSignalLog.onesignalLog(.LL_ERROR, message: "isCurrentUser called with empty externalId or no user instance")
             return false
         }
 
-        return user.identityModel.externalId == externalId
+        return userInstance.identityModel.externalId == externalId
     }
     /**
      Clears the existing user's data in preparation for hydration via a fetch user call.