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What is Unity Background Service?

Unity Background Service is a project that shows how to create an Android service for Unity application working on background. Usually Android service (especially in Unity apps) shuts down when we kill the app. It is impossible to make the service working fully on background. The only solution is to let the service work on foreground as a notification and then the users are able to hide that notification if they wants to. Specifically, this project shows the creation of a step counting service that works on background.

How to use?

How it works?

Unity

The main scene is located in Assets/Scenes. To see the example code go to BackgroundService class. Explanation of the methods:

1. On Awake the SendActivityReference method is called. It creates the Unity Android class and Unity activity. Then it sends the current activity to the plugin (the .aar file should be located at Assets/Plugins/Android)

void SendActivityReference(string packageName)
    {
        unityClass = new AndroidJavaClass("com.unity3d.player.UnityPlayer");
        unityActivity = unityClass.GetStatic<AndroidJavaObject>("currentActivity");
        customClass = new AndroidJavaClass(packageName);
        customClass.CallStatic("receiveActivityInstance", unityActivity);
    }

2. StartService and StopService methods respectively starts and stops the background service as well as GetCurrentSteps method simply gets the walked steps from plugin.
3. SyncData method returns a string data that holds 3 variables separated with # symbol:

• date of StartService method invocation
• date of SyncData method invocation
• count of steps walked during this period

public void SyncData()
    {
        string data;
        data = customClass.CallStatic<string>("SyncData");
        
        string[] parsedData = data.Split('#');
        string dateOfSync=parsedData[0] + " - " + parsedData[1];
        syncedDateText.text = dateOfSync;
        int receivedSteps = Int32.Parse(parsedData[2]);
        int prefsSteps = PlayerPrefs.GetInt(_prlayerPrefsTotalSteps,0);
        int prefsStepsToSave = prefsSteps + receivedSteps;
        PlayerPrefs.SetInt(_prlayerPrefsTotalSteps,prefsStepsToSave);
        totalStepsText.text = prefsStepsToSave.ToString();
        
        GetCurrentSteps();
    }

Android

The entry point of the Android application is the Bridge class. Explanation of the methods:

1. The receiveActivityInstance method is called when the SendActivityReference from Unity executes. It takes the Unity activity to know where to start the background service in the future. Also it checks if the permission for activity recognition is granted and asks for the permission if it is not (this logic is implemented for Android API 28 and above).

public static void receiveActivityInstance(Activity tempActivity) {
        myActivity = tempActivity;
        String[] perms= new String[1];
        perms[0]=Manifest.permission.ACTIVITY_RECOGNITION;
        if (ContextCompat.checkSelfPermission(myActivity, Manifest.permission.ACTIVITY_RECOGNITION)
                != PackageManager.PERMISSION_GRANTED) {
            Log.i("PEDOMETER", "Permision isnt granted!");
            ActivityCompat.requestPermissions(Bridge.myActivity,
                    perms,
                    1);
        }
    }

2. GetCurrentSteps is called when the GetCurrentSteps is called from Unity.