This webinar presentation covers how to use the Windows Phone SDK 8.0 in developing applications that will work for both Windows Phone 8 and Windows Phone 7. Michael Samarin of Futurice explains how to update your existing Windows Phone 7 application by adding new features using APIs available in Windows Phone 8. He also describes how to create a Windows Phone 8 application and make it work for Windows Phone 7 users. An overview of the available approaches to multirelease compatibility is provided along with useful tips and tricks to help you make the most of the Windows Phone market.

1. LUMIA APP LABS #5
DEVELOP APPS THAT WORK
FOR BOTH WINDOWS
PHONE 8 AND WINDOWS
PHONE 7
Michael Samarin
Director,
Developer Training
Futurice Ltd.
http://www.futurice.com

2. LUMIA APP LABS #5
- Windows Phone 8 is new development
platform
- Opportunity for developers to target both
Windows Phone 7 and 8, because of
installed base and similarities of platforms
- Windows Phone 7 code works without
changes, but with potential alterations in
runtime behavior
- Like with any cross platform development, there is no magic, but
creative thinking and hard work for developers
- Identify unique aspects and APIs of Windows Phone 8 that are
specific to your app
- Always try to decouple UI from business logic as much as you can

3. LUMIA APP LABS #5
Important MSDN Resources when
targeting both platforms WP7 / 8:
What’s new in Windows Phone 8:
http://msdn.microsoft.com/en-us/library/windowsphone/develop/jj206940(v=vs.105).aspx
Multi-resolution Apps:
http://msdn.microsoft.com/en-US/library/windowsphone/develop/jj206974(v=vs.105).aspx
How to upgrade an app project to Windows Phone 8:
http://msdn.microsoft.com/en-us/library/windowsphone/develop/jj207030(v=vs.105).aspx
App platform compatibility:
http://msdn.microsoft.com/en-us/library/windowsphone/develop/jj206947(v=vs.105).aspx

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Multiple Resolutions on Windows Phone devices (MSDN):
Delta from
Aspect Scaled
Resolution Resolution Windows Phone
ratio resolution
OS 7.1
None. This is the
only supported
WVGA 480 × 800 15:9 resolution for 480 × 800
Windows Phone
OS 7.1.
WXGA 768 × 1280 15:9 1.6x scale 480 × 800
1.5x scale, 80
pixels taller (53
720p 720 × 1280 16:9 480 × 853
pixels, after
scaling)
Multi-resolution Apps:
http://msdn.microsoft.com/en-US/library/windowsphone/develop/jj206974(v=vs.105).aspx

5. LUMIA APP LABS #5
Option #1
• Develop Windows Phone 7 (WP7) App
• Single project with WP7 build target
• Deploy to both WP7 / 8
• Be aware of “quirks mode” and breaking changes when
deploying to WP8
• Study carefully app platform compatibility:
http://msdn.microsoft.com/en-
us/library/windowsphone/develop/jj206947(v=vs.105).aspx

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Option #2
• Develop Windows Phone 7 (WP7) App
• Single project with WP7 build target
• Duplicate project and upgrade to WP8
• Maintain separate projects and build to both WP7 / 8
• Study carefully potential upgrade issues:
http://msdn.microsoft.com/en-us/library/windowsphone/develop/jj207030(v=vs.105).aspx

7. LUMIA APP LABS #5
Option #3
• Develop and maintain separate WP7 and WP8
projects
• Isolate reusable code into separate class files
• Add classes as linked files to both projects
• Use if needed compile time and runtime
conditions:
#if WINDOWS_PHONE7 if (Environment.OSVersion.Version.Major < 8)
... {
#elif WINDOWS_PHONE8 ....
.... }
#endif

8. LUMIA APP LABS #5
Option #4 (Only with VS Pro)
• Develop and maintain separate WP7 and WP8
projects
• Create project type Portable Class Library
• Isolate reusable code into Portable Class
Library
• Add Portable Class Library as reference to
both projects
• Can be used even without recompilation

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HANDS-ON SESSION
To view the demonstration, please refer to
the webinar recording at the end of this
slideset.

10. LUMIA APP LABS #5
THANK YOU!
@MichaelSamarin
http://www.futurice.com