Read original post at Nick's .NET Travels
The title of this post sounds a little weird but is actually quite fundamental to how you develop for Windows Phone. Most training content/courses for Windows Phone seem to focus unnecessarily on the application wide events of launching, closing, activating and deactivating. These are useful to get an understanding of what tombstoning is and why it happens. However, in most cases what’s more important is knowing and understanding the page methods which you can override to intercept the page lifecycle, namely OnNavigatedTo and OnNavigatedFrom. These methods always occur as a pair and as such make a useful point at which to save and restore page data.