Comment Feed for Channel 9 - Tombstoning and Task Switching - Day 3 - Part 8

Re: Tombstoning and Task Switching - Day 3 - Part 8

dwrogers — Fri, 19 Nov 2010 06:00:54 GMT

Does App.xaml.cs.SaveState() also need to use TryGetValue, since, the first time it is run, if we leave the page or hit start before we change the TextBox, there is nothing in the property bag and the access fails with an exception?

posted by dwrogers

Re: Tombstoning and Task Switching - Day 3 - Part 8

dwrogers — Sat, 20 Nov 2010 00:54:35 GMT

The sequence of Load, Activate, Deactivate, and Close calls was not obvious at first. And the fact that the debugger keeps dropping out makes it tough to follow. A useful extension to this module would be to record each of these events (WHEN it occurred) in the string we are saving.

These changes would go in App.xaml.cs:

        private void Application_Launching(object sender, LaunchingEventArgs e)
        {
            LoadState("L");
        }

        private void Application_Activated(object sender, ActivatedEventArgs e)
        {
            LoadState("A");
        }

        private void Application_Deactivated(object sender, DeactivatedEventArgs e)
        {
            SaveState("D");
        }

        private void Application_Closing(object sender, ClosingEventArgs e)
        {
            SaveState("C");
        }

And then:

        private void SaveState(string when)
        {
            PhoneApplicationService phoneAppService = PhoneApplicationService.Current;
            IsolatedStorageSettings settings = IsolatedStorageSettings.ApplicationSettings;

            if (phoneAppService.State.ContainsKey("MyValue"))
            {
                settings["MyValue"] = phoneAppService.State["MyValue"] + " " + when + " ";
            }
            else
            {
                settings["MyValue"] = when + " ";
            }

}

        private void LoadState(string when)
        {
            PhoneApplicationService phoneAppService = PhoneApplicationService.Current;
            IsolatedStorageSettings settings = IsolatedStorageSettings.ApplicationSettings;

            if (settings.Contains("MyValue"))
            {
                phoneAppService.State["MyValue"] = settings["MyValue"] + " " + when + " ";
            }
            else
            {
                phoneAppService.State["MyValue"] = when + " ";
            }
        }

David

posted by dwrogers

Re: Tombstoning and Task Switching - Day 3 - Part 8

ChannelFennel — Fri, 31 Dec 2010 22:52:19 GMT

12:12: It is unnecessary to condition 'TryGetValue' with 'ContainsKey' ('TryGetValue' combines 'ContainsKey' and 'Item' getter, see http://msdn.microsoft.com/en-us/library/bb347013(VS.95).aspx).

posted by ChannelFennel

Re: Tombstoning and Task Switching - Day 3 - Part 8

Mintydog — Tue, 18 Jan 2011 22:22:00 GMT

great video, thanks.

posted by Mintydog

Re: Tombstoning and Task Switching - Day 3 - Part 8

Dani50 — Fri, 04 Feb 2011 10:42:15 GMT

A very useful video but I have a question: I got the impression from the diagram on the link

http://msdn.microsoft.com/en-us/library/ff817008(v=VS.92).aspx">http://msdn.microsoft.com/en-us/library/ff817008(v=VS.92).aspx which is part of the instructions for submission that we are not "allowed" to run any code in the lauch event handler. This is the best place to run the LoadState() code as it is only done once. Are you able to clarify?

Dani.

posted by Dani50

Re: Tombstoning and Task Switching - Day 3 - Part 8

minompi — Fri, 18 Feb 2011 11:47:38 GMT

Very good! very simple and useful. Thanks a lot!

posted by minompi

Re: Tombstoning and Task Switching - Day 3 - Part 8

Charlie — Mon, 07 Mar 2011 01:45:38 GMT

I have tried this with the Simple Note application, which is the homework of day 3.

But whenever I press the start button, the app crashes and an error appears in the c# code.
I have tried the code of dwrogers, and it doesn't do anything at all.
So, is there any solution, as this is vital to me?.

posted by Charlie

Re: Tombstoning and Task Switching - Day 3 - Part 8

WayneHoggett — Mon, 18 Apr 2011 10:43:38 GMT

Got this to work on my second attempt! One of the harder lessons so far.

posted by WayneHoggett

Re: Tombstoning and Task Switching - Day 3 - Part 8

Vesku — Mon, 23 May 2011 12:22:40 GMT

I think I've done exactly as Bob instructed, but when I type something in the text box, tap the Windows key and then return to the application, the text has gone. Same with the Back key. Can't figure out what the difference could be.

posted by Vesku

Re: Tombstoning and Task Switching - Day 3 - Part 8

MartinCZ — Sat, 20 Aug 2011 17:23:27 GMT

Hi, here is the way how to have the testing device always set to Emulator.

http://www.pchenry.com/Home/tabid/36/EntryId/412/Tired-of-ALWAYS-having-to-change-to-the-WP7-emulator-in-Visual-Studio.aspx

posted by MartinCZ

Re: Tombstoning and Task Switching - Day 3 - Part 8

golnazal — Mon, 26 Mar 2012 21:38:42 GMT

posted by golnazal

Re: Tombstoning and Task Switching - Day 3 - Part 8

Atcold — Mon, 26 Mar 2012 21:48:45 GMT

I came across to the same problem of Vesku (May 23, 2011 at 5:22 AM) and I (not easily) solved it. Shortly, the line of code

if (phoneAppService.State.ContainsKey("MyValue"))

in the LoadState() method should be commented (or deleted). This solves the problem. I know the app in the video works but it can be easily a bug that has been corrected with the newest releases of Silverlight or whatsoever.

posted by Atcold