How early can session didReceiveApplicationContext be called on the iPhone app as it launches

Question

In my phone app, the WCSession is activated within the AppDelegate's didFinishLaunchingWithOptions method. The watch app is sending an applicationContext to the phone app. Suppose the phone app is not running at the time of this transfer, and when the phone app is launched later, how early can the call to didReceiveApplicationContext come into the phone app? I am not worried about the delay or how late it arrives. I am wondering if there is a possibility that the call can come in before the rootViewController's viewDidLoad method runs. Can this session event get into the event loop somewhere in between the events of UIWindow creation and the viewDidLoad on the rootViewController, as the app is launching on the phone?

In my tests with the apps on real devices, it happened always after the viewDidLoad invocation but often before the AppDelegate's applicationDidBecomeActive.

I am using a storyboard. However I am interested in learning any possible differences, had the main view been created in the code. Also the actions within the didReceiveApplicationContext do not touch any of the views or subviews. It just stores the data and notifies any registered view controllers.

Answer 1

So far I have not found any explicit or implicit guarantee as to when the buffered applicationContext will be delivered to the phone, as it launches. By explicit, I am referring to any documented data on the order of the events (say, only after the app becomes active). By implicit, what I mean is any logical inference based on the knowledge of the main run loop as well as the start time events of an app, which can assure that the delivery will no way be attempted before a certain stage in the launch process. As such, I will just note down my observations here.

When I used only the applicationContext to pass data to a non-running app on the iPhone, it always got delivered after the viewDidLoad method call on the rootViewController, as and when the phone app eventually launched. However, if I perform a sendMessage from watch to phone following a sendApplicationContext, it would wake up the app on the phone as expected. At this time, the buffered applicationContext sometimes seems to get delivered to the phone even before loading the view of the rootViewController.