1. Windows Runtime App Lifecycle
WinRT Apps
Building Apps for Windows Phone 8.1 Jump Start
Building Windows Runtime Apps using C# and XAML
Windows Runtime App Lifecycle

2. In this module… Windows Runtime App Lifecycle
Launch
Suspend
Resume
Termination
Saving and Restoring State

3. Lifecycle? phone resources are scarce (battery especially)
OS runs one foreground app at a time
other apps are suspended and/or terminated
OS has many mechanisms for an app to appear ‘alive’
OS has controlled mechanisms for background code

4. Lifecycle? lifecycle is very similar to Windows 8.1 app lifecycle
differences due to the nature of Phone hardware and the need to maintain compatibility with WP8.0, WP7.x apps
different from Windows Phone 8.0 app lifecycle
concepts will be familiar to any mobile app developer

5. launch, suspend, resume

6. User launches app
Launch
Running
NotRunning

7. Application.OnLaunched override
sealed partial class App : Application {
/// <summary>
/// Invoked when the application is launched normally by the end user.
/// </summary>
/// <param name="e">Details about the launch request and process.</param>
protected override async void OnLaunched(LaunchActivatedEventArgs e)
// How did the app exit the last time it was run (if at all)
ApplicationExecutionState previousState = e.PreviousExecutionState;
// What kind of launch is this?
ActivationKind activationKind = e.Kind;
// ...
NotRunning
Running
Suspended
Terminated
ClosedByUser
Launch
File
Protocol
VoiceCommand
Etc.

8. User navigates away from your app
App is suspended
All code stopped
No timers tick
No events fire
Process still alive and in memory
Code has a chance to respond (next slide)
Leaves App

9. Application.Suspending event
This code has limited time to run. Doing the minimum amount of work here will improve the user’s experience of your app.
NB: Only ask for a deferral if you are doing async work. A deferral does not give you any more time to suspend.
sealed partial class App : Application {
public App()
this.InitializeComponent();
this.Suspending += OnSuspending; }
private async void OnSuspending(object sender, SuspendingEventArgs e)
// Ask for a deferral if you need to do async work
var deferral = e.SuspendingOperation.GetDeferral();
// TODO: whatever async work you need to do when suspending
deferral.Complete(); // Then mark the deferral complete

10. User returns to your app
Same app is resumed
Same process, same memory so values of variables are intact
All code runs
Code has a chance to respond...
Back
Launch
Switcher

11. Application.Resuming event
12/31/2018
Application.Resuming event
sealed partial class App : Application {
public App()
this.InitializeComponent();
this.Suspending += OnSuspending;
this.Resuming += OnResuming; }
private void OnResuming(object sender, object e)
// TODO: whatever you need to do to resume your app
© 2013 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

12. The debugger is/isn’t your friend 
By design - your code will not suspend/resume under the debugger 
The debugger has a specific feature to simulate suspend/resume 

13. What to do on resuming?
Check external data or conditions that might change while the app was suspended
Possibly factoring in the time elapsed between suspension and resumption
Examples (taken from
refresh data from an online source
refresh the app’s view of connectivity – online or offline?
refresh sensor data such as compass, geolocation
retry a networking call that may have failed while suspended
refresh layout – device may have reorientated since suspension
check for new data populated by background tasks or system roaming

14. Apps can be closed by the user
ClosedByUser
Running
NB: Back button does not close the app

15. Demo

16. Termination

17. The OS can terminate your app
System has a priority system for determining which app to terminate.
User Runs
Another App
OS Short of
Memory
OS Terminates
An App
Terminated

18. The OS can terminate your app
OS does not wake an app to terminate it – no notification
App is removed from task switcher list

19. User ‘returns’ to a terminated app
User will be unaware that the app was terminated
Would often expect that their experience simply continues
The developers’ job is to maintain the illusion that the app has always been running, even though it hasn’t

20. User ‘returns’ to a terminated app
User must not lose data & should continue recent activity seamlessly
App may need to restore transient session state
Includes page navigation history, page position/parameters & contents of input fields
Every app defines ‘recent’ differently

21. Transient data versus persistent data
12:38
Work
Tel:
Home
Tel:
CONTACTS
Jim Jones
12:38
CONTACTS
Add Phone
Mobile Phone
Phone type
Phone number
App Data Local Folder
(or roaming folder for Data)
12:38
CONTACTS
all
Data
12:38
Jim Jones
Tel:
Bob Brown
Tel:
Arthur Abbott
Tel:
State
Navigate(Page2, ID param)
Navigate(Page3, ID param)

22. Demo

23. Help from the framework & templates
The Frame class has [Get/Set]NavigationState method to (re)store navigation history as a String
The SuspensionManager class helps with (re)storing global & Frame state in a file
The NavigationHelper class wires the Page to the SuspensionManager via easy page-level events
the last 2 classes are not in the blank template, you need to add “basic page” items or use another template to get them

24. For a clean, new launch of the app...
12/31/2018
For a clean, new launch of the app...
OnLaunched
App
Frame
Suspension
Manager
RegisterFrame()
allows suspension manager to;
get/set navigation history
be aware as the Frame is navigating
© 2013 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

25. Only if the app was previously terminated
12/31/2018
Only if the app was previously terminated
OnLaunched
App
Suspension
Manager
RestoreAsync()
© 2013 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

26. this history is tracked by the Frame. parameters must be serializable.
12/31/2018
as the app navigates
state dictionaries owned by SuspensionManager. entries must be serializable
Page A
Navigation
Helper
LoadState(
Parameter,
null /* dictionary */ );
Navigate(PageA, Parameter)
this history is tracked by the Frame. parameters must be serializable.
© 2013 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

27. 12/31/2018
save all state necessary to reconstruct as page may not be cached and/or app may be terminated before page is revisited.
as the app navigates
Page A
Page B
Navigation
Helper
LoadState(
Parameter,
null /*dictionary*/ );
Navigate(PageB, Parameter)
SaveState(
dictionary );
Navigation
Helper
© 2013 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

28. 12/31/2018
page may be a new or a cached instance. depends on cache mode & memory.
as the app navigates
Page A
Navigation
Helper
Page B
GoBack()
LoadState(
parameter,
dictionary );
SaveState(
dictionary );
Navigation
Helper
© 2013 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

29. as the app navigates null dictionary? - reset controls to defaults.
12/31/2018
as the app navigates
null dictionary? - reset controls to defaults.
non null dictionary? – restore control state.
Page A
Page B
Navigation
Helper
LoadState(
Parameter,
dictionary );
GoForward()
SaveState(
dictionary );
Navigation
Helper
© 2013 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

30. as the app suspends ... Suspending App Suspension Manager SaveAsync()
12/31/2018
as the app suspends
Suspending
App
Suspension
Manager
SaveAsync()
State Dictionaries
Global
Frame 1
Page 1
...
© 2013 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

31. ‘Recent’ state with SuspensionManager
On startup, you might want a previously terminated app to discard state and start afresh (example: state is not “recent” enough)
Can modify SuspensionManager to add this capability

32. Demo

33. Related topics Notification mechanisms
12/31/2018
Related topics
Notification mechanisms
Session 10: Tiles, badges, Toasts and Action Center
Additional activation scenarios – e.g. protocol activation
Session 14: Sharing Files and Data
Background working
Session 11: Background Tasks
Application Lifecycle in Silverlight Apps
Building Apps for Windows Phone 8 Jump Start - Session 5: Windows Phone 8 Application Lifecycle
© 2013 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.