***************
CoreApplication
***************

In every scene using either the RestAPI, the CrossPromo or the ScalableServer, there should be
an object with the ``CoreApplication`` component. This is a singleton that will
eventually manage every aspect of the SDK.

``CoreApplication`` is the single point of access to core components:

- Scene transitions
- Event messaging system
- Analytics
- Network parameters
- ...

It can also run Coroutines for objects that are not MonoBehaviours.

Integration in your game
------------------------

In your scene:

- Add an empty object
- Add the ``CoreApplication`` component to it. This will automatically add all
  the other components it requires.

**You should save this object as a prefab to re-use in other scenes.**

.. image:: ../Images/coreapplication-image1.png

One Singleton to rule them all
------------------------------

The CoreApplication is a GameObject marked as `DontDestroyOnLoad`. It's a singleton and the first
instance created during a session will live until you stop your game.
If you followed the good practice of adding a ``CoreApplication`` prefab in all you scenes, the ``CoreApplication``
you keep at runtime is the one from the first scene loaded.

Extending with your own elements
--------------------------------

Having multiple singletons in an application is usually a bad idea. They are often written in different ways by several developers and subtile bugs can appear. 

That's why we created the ``CoreApplication`` component.

If you have you own singletons, core managers... you can easily access them from the ``CoreApplication``. Create a subclass of ``CoreApplicationDelegate`` with a property to access your singleton and simply replace the one we automatically add to ``CoreApplication``.

This way you will be able to write:

.. code:: csharp

	MyCustomDelegate delegate = (MyCustomDelegate)CoreApplication.Instance.CoreApplicationDelegate;
	delegate.MyCustomSingleton.DoSomething();

Coroutine
---------

The ``CoreApplication.ExecuteCoroutine(IEnumerator action)`` method is a Coroutine facilitator.
It allows to execute Coroutines in Play Mode, even if CoreApplication instance doesn't exist (like in Play Mode tests).