NSC AD 340 5210 - Week 8

Transcript

1. Week 8
   Lecture
   ViewBinding, ViewModel and
   MVVM
   

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2. What are we building
   this week?
   Replacing findViewById() using
   ViewBinding
   02
   Project Demo ViewBinding
   01
   Saving data across configuration
   changes
   ViewModel Scoping
   04
   Android ViewModel
   Implementing MVVM using
   Android ViewModel
   03
   

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3. Project Demo
   What are we building
   this week?
   

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4. Week 8 Project
   Updates
   ● Refactoring ForecastDetailsFragment
   ● Using ViewBinding to replace calls to findViewById()
   ● Using ViewModel to implement MVVM
   ● Saving data across configuration changes using ViewModel scoping
   

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5. ViewBinding
   Replacing calls to
   findViewById()
   

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6. Generate statically
   typed view references
   Removes any need for findViewById()
   

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7. Access Generated View Properties
   // inflate layout and get ViewBinding reference
   val binding = FragmentForecastDetailsBinding.inflate(inflater, parent, false)
   // access null-safe properties to reference you views
   binding.descriptionText.text = viewState.description
   binding.dateText.text = viewState.date
   binding.forecastIcon.load(viewState.iconUrl)
   

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8. Enable ViewBinding
   // app/build.gradle
   android {
   …
   viewBinding {
   enabled = true
   }
   }
   

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9. ViewModel
   Separating business logic from
   UI presentation
   

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10. “The ViewModel class is designed to store and
    manage UI-related data in a lifecycle conscious
    way. The ViewModel class allows data to survive
    configuration changes such as screen rotations”
    

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11. ● Manage data sources
    ● Format data
    ● Save data across configuration change
    ● Expose data to be displayed in the UI
    Using ViewModel
    

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12. MVVM
    Separation of business logic and UI
    presentation
    

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13. MVVM
    VIEW VIEW MODEL MODEL
    

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14. MVVM
    FRAGMENT VIEW MODEL REPOSITORIES
    

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15. ViewModel
    Scoping
    Save data across
    configuration changes
    

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16. ● Avoid creating a new ViewModel in response to
    configuration changes
    ● Reuse existing ViewModels (and data) within
    different scopes
    ○ Fragment
    ○ Activity
    ○ Navigation Graph
    ViewModel Scoping
    

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17. ● More responsive apps
    ● Fewer network and database requests
    ● Better user experience
    ViewModel Scoping
    

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18. Demo
    

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