Tombstoning the last visited page the user was on - silverlight

Question

I want to tombstone the last page that the user was on and to retrieve it when the user comes back to the app. All of the tombstoning examples on the Internet deal with saving some data or the state of the page that the user has edited somehow (i.e inputed text in the textbox). In my app I don't have anything for the user to modify/edit so I just want to save the last visited page that the user was on. I tried to use some online examples that used PhoneApplicationService.Current.State but with no success.
Thank you to anyone who would like to help me out resolving this issue!

Answer 1

To locally store persistent data (data that should remain even when the user closes the app), you can use Isolated Storage.
So, in your app's Deactivated event, you can write the page's name to Isolated Storage like this:
//You get the Isolated Storage for your app (other apps can't access it)
IsolatedStorageFile isf = IsolatedStorageFile.GetUserStoreForApplication();
//if the file already exists, delete it (since we're going to write a new one)
if (isf.FileExists("lastpage.txt")) isf.DeleteFile("lastpage.txt");
using (var isoFileStream = new IsolatedStorageFileStream("lastpage.txt", FileMode.OpenOrCreate, isf))
{
//open a StreamWriter to write the file
using (var sw = new StreamWriter(isoFileStream))
{
//NavigationService.CurrentSource returns the current page
//we can write this to the file
sw.WriteLine((Application.Current.RootVisual as PhoneApplicationFrame).CurrentSource.ToString());
}
}
This will write the current page's name to the Isolated Storage. Then, in your OnNavigatedto method of your main page (the page that first opens normally) you can read the file name and navigate to it:
protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e)
{
IsolatedStorageFile isf = IsolatedStorageFile.GetUserStoreForApplication();
string lastpage = string.Empty;
if (isf.FileExists("lastpage.txt"))
{
using (var isoFileStream = new IsolatedStorageFileStream("lastpage.txt", FileMode.Open, isf))
{
//read the file using a StreamReader
using (var sr = new StreamReader(isoFileStream))
{
//get the uri we wrote and then convert it from a String to a Uri
lastpage = sr.ReadLine().Replace("file:///", "");
}
}
(Application.Current.RootVisual as PhoneApplicationFrame).Navigate(new Uri(lastpage, UriKind.Relative));
}
base.OnNavigatedTo(e);
}
This should read in the file you saved and then convert the string into an actual URI that you can pass to the NavigationService.
You can then delete the text file after it's been read so that it doesn't always keep jumping to that page.

Answer 2

In addition you can use this for getting the page name ,string PageName = (Application.Current.RootVisual as PhoneApplicationPage).Name; for getting the current page name

Answer 3

While I agree all the above options are possible, they are not really the correct way of doing something within a WP7.
It's better to construct a navigation page at the start of your app for properly controlling navigation, it also helps with managing back key events while using the app and prevents hiccups.
See Here for one example of implementing this:
Properly Exiting Silverlight-based WP7
With this done use the advice on storing values in isolated storage / application settings to then just store the "Current Page" state value (e.g. value of Page.GamePage) then the app navigation will direct you accordingly.
BUT beware when just storing the current page itself as you also need to save the correct state of any values or User entered data on that page when it tombstones as well, this the above advice should lead you in the right direction.
Hope this helps