Detect for timezone changes and update the user

* Unless users switch via logging in and out, we never update timezone (as it is only sent in the Create User request).
* Now, we cache timezone ID and detect for changes on cold starts and update the user when it changes.
* We also fix a rare issue that comes from upgrading from an old version of player model to user model. When we have a legacy player ID, we fetch its identity rather than creating a user. Thus, in some rare cases, this old player is already missing a timezone, and the SDK never calls Create User to set a timezone. As a result, this user will be missing timezone.
* As a one-time migration, we send up the timezone for all users without considering if timezone is indeed missing or not. Note that this update will be combined in the payload of the session_count update. This update is driven by reading the timezone_id from cache, but before this PR, timezone was never cached, so it will return null.

Author: nan-li

iOS_SDK/OneSignalSDK/OneSignalUser/Source/OSPropertiesModel.swift

@@ -63,7 +63,14 @@ class OSPropertiesModel: OSModel {
         }
     }
 
-    var timezoneId = TimeZone.current.identifier
+    var timezoneId: String? = TimeZone.current.identifier {
+        didSet {
+            guard timezoneId != oldValue else {
+                return
+            }
+            self.set(property: "timezone_id", newValue: timezoneId)
+        }
+    }
 
     var tags: [String: String] = [:]
     private let tagsLock = NSRecursiveLock()
@@ -90,13 +97,15 @@ class OSPropertiesModel: OSModel {
             super.encode(with: coder)
             coder.encode(language, forKey: "language")
             coder.encode(tags, forKey: "tags")
+            coder.encode(timezoneId, forKey: "timezoneId")
             // ... and more
         }
     }
 
     required init?(coder: NSCoder) {
         super.init(coder: coder)
         language = coder.decodeObject(forKey: "language") as? String
+        timezoneId = coder.decodeObject(forKey: "timezoneId") as? String
         guard let tags = coder.decodeObject(forKey: "tags") as? [String: String] else {
             // log error
             return
@@ -106,6 +115,10 @@ class OSPropertiesModel: OSModel {
         // ... and more
     }
 
+    func update() {
+        timezoneId = TimeZone.current.identifier
+    }
+
     /**
      Called to clear the model's data in preparation for hydration via a fetch user call.
      */

iOS_SDK/OneSignalSDK/OneSignalUser/Source/OSUserInternalImpl.swift

@@ -37,6 +37,7 @@ protocol OSUserInternal {
     var pushSubscriptionModel: OSSubscriptionModel { get }
     var identityModel: OSIdentityModel { get }
     var propertiesModel: OSPropertiesModel { get }
+    func update()
     // Aliases
     func addAliases(_ aliases: [String: String])
     func removeAliases(_ labels: [String])
@@ -72,6 +73,11 @@ class OSUserInternalImpl: NSObject, OSUserInternal {
         self.pushSubscriptionModel = pushSubscriptionModel
     }
 
+    func update() {
+        self.pushSubscriptionModel.update()
+        self.propertiesModel.update()
+    }
+
     // MARK: - Aliases
 
     /**

iOS_SDK/OneSignalSDK/OneSignalUser/Source/OneSignalUserManagerImpl.swift

@@ -256,7 +256,7 @@ public class OneSignalUserManagerImpl: NSObject, OneSignalUserManager {
         subscriptionModelStoreListener.start()
         pushSubscriptionModelStoreListener.start()
         if hasCachedUser {
-            _user?.pushSubscriptionModel.update()
+            _user?.update()
         }
     }
 
@@ -294,6 +294,18 @@ public class OneSignalUserManagerImpl: NSObject, OneSignalUserManager {
 
         // 3. Make the request
         userExecutor!.fetchIdentityBySubscription(newUser)
+
+        // 4. Send any updates to sync the local state
+        updateLegacyPlayer(newUser)
+    }
+
+    /**
+     Migrating a legacy player does not result in a Create User call, but certain local data should be sent manually.
+     */
+    private func updateLegacyPlayer(_ user: OSUserInternal) {
+        if let timezoneId = user.propertiesModel.timezoneId {
+            updatePropertiesDeltas(property: .timezone_id, value: timezoneId)
+        }
     }
 
     private func createNewUser(externalId: String?, token: String?) -> OSUserInternal {
@@ -567,6 +579,7 @@ extension OneSignalUserManagerImpl {
     /// It enqueues an OSDelta to the Operation Repo.
     /// 
     /// - Parameter property:Expected inputs are `.session_time"`, `.session_count"`, and `.purchases"`.
+    /// May be `.timezone_id` or others if the SDK is sending an update for a legacy player.
     func updatePropertiesDeltas(property: OSPropertiesSupportedProperty, value: Any, flush: Bool = false) {
         guard !OneSignalConfigManager.shouldAwaitAppIdAndLogMissingPrivacyConsent(forMethod: "updatePropertiesDeltas") else {
             return

iOS_SDK/OneSignalSDK/OneSignalUser/Source/Support/OSPropertiesSupportedProperty.swift

@@ -36,6 +36,7 @@ enum OSPropertiesSupportedProperty: String {
     case language
     case location
     case tags
+    case timezone_id
     // Created manually by User Manager, not through Models
     case session_count
     case session_time