WatchOS: getting applicationDidBecomeActive notifications
<p>I'm making a framework that needs to do stuff when my apple watch is entering background and foreground.</p>

<p>I'm looking for an equivalent of this iOS code for the Apple watch since UIApplication is not present in UIKit anymore : </p>

<pre><code>let notificationCenter = NSNotificationCenter.defaultCenter()
notificationCenter.addObserver(self, selector: "applicationDidEnterBackground", name: UIApplicationDidEnterBackgroundNotification, object: nil)
</code></pre>

<p>any help would be nice </p>