07 wp7 application lifecycle
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The document discusses the application lifecycle on mobile devices and how developers should handle interruptions, user expectations, and different lifecycle events. It covers topics like tombstoning, where the application is dead but some state is saved, and how restoring state is important for a good user experience. Code samples demonstrate saving state on deactivation and restoring it on activation. Managing resources properly during lifecycle events is required for apps to be published.
07 wp7 application lifecycle
- 2. AgendaInterruptions & User Expectations
- 4. Tombstoning
- 7. Play Time
- 8. Q & AInterruptionsInterruption comes from
- 9. A user action (i.e. press the start button)
- 10. An external event (an incoming phone call)
- 11. An internal action (i.e. taking a photo, choosing a contact)
- 13. Interruptions are not predictable
- 14. Interruptions tend to happen frequently User ExpectationsPhone and Applications
- 15. Phone is resource-constrained device, therefore we need to consume resources carefully
- 16. Phone is different from Desktop OS, which can hold multiple windows running processes simultaneously
- 17. However…
- 18. A user expects the application to be able to remain in the state where it was left
- 19. Microsoft development guideline requires application to provide such illusions that it keeps running continuously until it is get killedApplication LifecycleRunningDormantTombstonedDeactivatedDeactivatedDead, and no longer lives in memory.But with somethingcarved on a TombstonePhone resources detachedThreads & Timers suspendedBut app instance remains in memoryActivatede.Preserved == trueFast App ResumeActivatede.Preserved == falseYou Will See Resuming Process Bar
- 20. TombstoningWhen an app is tombstoned, it means
- 21. The app is dead
- 22. Some relevant data is saved by System for the app/page, which is called State information
- 23. When user navigates back
- 24. System restarts the application, passes applications state back to the App
- 25. System navigates to the very page where it was left, passes page state back to the Page
- 27. Write code to save state before the app gets tombstoned
- 28. Write code to restore state after the app is reactivated from tombstonedLifecycle Events - AppApplication_Launching
- 29. Fired when the application is started
- 30. Not fired when the application is reactivated
- 33. Fired when the application is reactivated (brought to foreground)
- 34. Not fired when the application is started
- 35. Restore app state if tombstoned
- 37. Fired when the application is deactivated (sent to background)
- 38. Not fired when the application is closed
- 39. Save app state as needed
- 41. Fired when the application is closing (i.e. user presses Back key)
- 42. Not fired when the application is deactivated
- 43. Save app settings/configurationLifecycle Events - PageOnNavigatedTo
- 44. Fired when the application is started
- 45. Not fired when the application is reactivated
- 46. Restore page state if tombstoned
- 47. OnNavigatedFrom
- 48. Fired when the application is deactivated (sent to background)
- 49. Not fired when the application is deactivated
- 50. Save page state as neededCode Sample - 1Application_Launching
- 51. Load app settings/configurationCode Sample - 2Application_Closing
- 52. You have only 10 seconds to finish all job
- 53. If you’ve got complex data to save, it’s recommended to save your data while the app is running at appropriate pointsCode Sample - 3Application_Deactivated
- 54. Save app state as neededCode Sample - 4Application_Activated
- 55. Restore app state if tombstonedTime Limits
- 56. Resource Management - 1Deactivating AppPage.OnNavigatedFrom- You may release phone resources, but not necessarily, the framework is doing it anyway- You MUST Save app/page stateApp.DeactivatedFramework:Detach ResourcesFramework:Suspend Timers and ThreadsDormant App
- 57. Resource Management - 2Running AppPage.OnNavigatedToMediaElement : Reset Source/Position
- 60. Restore app state if tombstonedApp.ActivatedFramework:Attach ResourcesFramework:Resume Timers and ThreadsDormant App
- 61. Take It SeriousIt is required, not just recommended !
- 62. Microsoft tries its best to keep apps in the line, providing consistent user experience to end users.
- 63. It is about money !
- 64. If your app does not handle lifecycle issues, then it will be disqualified to be published on marketplace.Play Time !Goals
- 65. To understand various lifecycle events and orders of occurring under different situations
- 66. To be able to store and retrieve state information
- 67. To understand how tombstoning worksTipTo test tombstoning on emulator! & ?Thank You ! Any Questions ?