1. Tom Opgenorth
Developer / Writer
Xamarin
tom.opgenorth@xamarin.com
Fragments - The Next Step
(Advanced Fragments)
@topgenorth

2. Topics to Look out For In this Session
• Quick Review of Fragments
• How Fragments can Help Their Host with State
• Not ONE But TWO Fragments :
DialogFragment
PreferenceFragment

3. Review

4. What Do We Need to Remember About
Fragments ?
• Fragments Are Modular UI
Think “mini-Activity”
• Hosted in an Activity
Statically - in Layout
Dynamically - at Runtime
• They inflate views (usually)
• They have a lifecycle

5. Retaining State

6. • Runtime / Changes kill Activities
State needs to be maintained
• Custom objects to maintain state
Subclass Java.Lang.Object
Override OnRetainNonConfigurationInstance
Check Activity.LastNonConfigurationInstance
But these are DEPRECATED!
Activity State Can Complex

7. - Leonardo da Vinci
Simplicity is the Ultimate Sophistication

8. this.RetainInstance = true;

9. How Does this Impact the Fragment
Lifecycle?
Start
OnInflate OnAttach
OnCreate
OnCreate
View
OnActivity
Created
OnStart
OnResume
OnPause
OnStop
OnDestroy
View
OnDestroy
OnDetachRunning
End

10. • Survives config changes!
• Lightweight
• Perfect for
Background Process (Threads)
Memory intensive Resources
Sharing Data
What Does This Mean - Exactly?

11. Demo 1

12. DialogFragment

13. Why Use DialogFragment?
• Configuration changes are hard on dialogs
Dialog Should Remain - but the Activity is destroyed
• Customizable
• “Managed Dialogs” - Old School

14. How Do I Use DialogFragments?
• Subclass DialogFragment
• Override one of the following methods:
OnCreateDialog
• A “proper” dialog will pop up
OnCreateView
• Inflate a View - then embed it
• Modal, but not blocking

15. Demo 2

16. Preference
Fragment

17. PreferenceFragment : Why Do I Care?
• Preferred Way for Android 3.0 or Higher
• Can Share Across Activities
• Allows for Hierarchies
PreferenceActivity Does Not

18. On A Tablet

19. On a Phone

21. Demo 3

22. What Were We Talking About Again?
• Keep Fragments around with RetainInstance
• DialogFragments
Dialog or Embedded
Modal but not Blocking!
• PreferenceFragment

23. Q & A

24. THANK YOU