[UTY-1613] Gracefully handle disconnect in Playground (#686)

* Handle disconnect gracefully on mobile clients

* Addressing PR feedback

* Adding changelog entry

Author: gkassabli

CHANGELOG.md

@@ -8,6 +8,7 @@
 - Added support for the Alpha Locator flow.
 - Added support for connecting mobile devices to cloud deployments via the anonymous authentication flow.
 - Added option to build workers out via IL2CPP in the cmd.
+- Added an example of handling disconnect for mobile workers.
 
 ### Changed
 

workers/unity/Assets/Playground/Scripts/Camera/InitCameraSystem.cs

@@ -36,7 +36,15 @@ protected override void OnUpdate()
                 PostUpdateCommands.AddComponent(entity, CameraComponentDefaults.Transform);
 
                 Cursor.lockState = CursorLockMode.Locked;
+
+                // Disable system after first run.
+                Enabled = false;
             }
         }
+
+        protected override void OnDestroyManager()
+        {
+            Cursor.lockState = CursorLockMode.None;
+        }
     }
 }

workers/unity/Assets/Playground/Scripts/UI/ConnectionScreenController.cs

@@ -59,6 +59,13 @@ public void OnConnectionFailed(string connectionError)
                 $"Connection failed. Please check the IP address entered.\nSpatialOS error message:\n{connectionError}";
         }
 
+        public void OnDisconnected(string disconnectReason)
+        {
+            UnityObjectDestroyer.Destroy(worker);
+            ipAddressInput.text = PlayerPrefs.GetString(HostIpPlayerPrefsKey);
+            connectionPanel.SetActive(true);
+        }
+
         private IMobileConnectionController PrepareConnect()
         {
             errorMessage.text = string.Empty;

workers/unity/Assets/Playground/Scripts/UI/InitUISystem.cs

@@ -45,5 +45,10 @@ protected override void OnUpdate()
             // Disable system after first run.
             Enabled = false;
         }
+
+        protected override void OnDestroyManager()
+        {
+            UnityObjectDestroyer.Destroy(UIComponent.Main.gameObject);
+        }
     }
 }

workers/unity/Assets/Playground/Scripts/Worker/AndroidClientWorkerConnector.cs

@@ -28,6 +28,7 @@ public async void TryConnectAsync(ConnectionService connectionService)
         protected override void HandleWorkerConnectionEstablished()
         {
             ConnectionScreenController.OnConnectionSucceeded();
+            Worker.OnDisconnect += ConnectionScreenController.OnDisconnected;
             WorkerUtils.AddClientSystems(Worker.World);
 
             if (level == null)

workers/unity/Assets/Playground/Scripts/Worker/iOSClientWorkerConnector.cs

@@ -27,6 +27,7 @@ public async void TryConnectAsync(ConnectionService connectionService)
         protected override void HandleWorkerConnectionEstablished()
         {
             ConnectionScreenController.OnConnectionSucceeded();
+            Worker.OnDisconnect += ConnectionScreenController.OnDisconnected;
             WorkerUtils.AddClientSystems(Worker.World);
 
             if (level == null)