05 wp7 launchers and choosers

Launchers
and
Choosers
Jason Lee
Ethos Technologies

Agenda
Introduction
Full List
Code Example
Execution Model
Event Flow
Play Time
Q & A

Launchers & Choosers
Windows Phone provides a number of functions
Telephone Call, SMS, Email, Camera, Contacts etc.
Indirect access to phone features & data
Applications can NOT directly access information such as contacts.
Applications can NOT directly execute behaviors such as phone call or SMS.
Launchers & Choosers allow applications to access various phone features and data through them.
They invoke new applications
Launcher & Chooser APIs invoke distinct built-in applications (which in turn replace the currently running application, and can go back by hitting Back key)

Launcher
A Launcher
Launches one of the built-in applications through which a user can complete a certain task
No data is returned to calling application
Examples :
PhoneCallTask
SMSComposeTask

Chooser
A Chooser
Also launches one of the built-in applications through which a user can complete a certain task
Returns some data to calling application
When a chooser completes, calling application is reactivated and supplied with the result
A user can cancel the launcher, in which case an empty value is returned
Examples :
PhoneNumberChooserTask
PhotoChooserTask

Full List

Using Launchers
Key Points
Different launchers has different parameters
They all have a Show() method to invoke tasks
Example 1
Example 2

Using Choosers
Key Points
Hook to a Chooser’s Completed event for result data
Use Show() method to invoke tasks
Example

Execution Model
When Launchers & Choosers are hit
OnNavigatedFrom event occurs to the page
Deactivated event occurs to the App
Control switches to the task
While Launchers & Choosers running
There’s no guarantee that the user will come back to your app
If the user navigates away from the task, your app will be dormant, and therefore has a possibility to be tombstoned eventually
Thus, every stateful application should handle tombstoning
After Launchers & Choosers complete
Activated event occurs to App
OnNavigatedTo event occurs to the page
The app and page are the same instances if not tombstoned, new instances if tombstoned.

Event Flow
Without Tombstoning
App
Page
Task
App()
Launching
Page()
OnNavigatedTo
Show()
OnNavigatedFrom
Deactivated
Do Something
Activated
Completed
OnNavigatedTo

Event Flow
With Tombstoning
App
Page
Task
App()
Launching
Page()
OnNavigatedTo
Show()
OnNavigatedFrom
Deactivated
Navigates Away
and
Come Back
App()
Activated
Page()
OnNavigatedTo
Completed Event does NOT occur

Play Time !
Goals
Get familiar with various Launchers and Choosers
Understand application lifecycle event flow related to Launchers and Choosers

! & ?
Thank You !
Any Questions ?

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05 wp7 launchers and choosers

by Tao on Jul 19, 2011

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05 wp7 launchers and choosers — Presentation Transcript