OnDisappearing and OnAppearing overrides cannot be treated as guaranteed indications of page navigation? Xamarin.Forms
<p>I am adding navigation to a Xamarin.Forms application. I need a method gets executed every time I am navigating away from a page. I want to override the <a href="https://developer.xamarin.com/api/member/Xamarin.Forms.Page.OnDisappearing/" rel="nofollow noreferrer">OnDisappearing</a> method from the <a href="https://developer.xamarin.com/api/type/Xamarin.Forms.Page/" rel="nofollow noreferrer">Page</a> base class. The problem is that in the online Xamarin book, on the <a href="https://developer.xamarin.com/guides/xamarin-forms/user-interface/navigation/hierarchical/" rel="nofollow noreferrer">navigation chapter</a> I found this statement: </p>

<blockquote>
  <p>Calls to the <a href="https://developer.xamarin.com/api/member/Xamarin.Forms.Page.OnDisappearing/" rel="nofollow noreferrer">OnDisappearing</a> and <a href="https://developer.xamarin.com/api/member/Xamarin.Forms.Page.OnAppearing/" rel="nofollow noreferrer">OnAppearing</a> overrides cannot be
  treated as guaranteed indications of page navigation. For example, on
  iOS, the OnDisappearing override is called on the active page when the
  application terminates.</p>
</blockquote>

<p>Does this mean that the OnDesappeating method does not get executed every single time right when navigating to another page?</p>