An Android Dev start to Kotlin MPP

Transcript

1. An Android Dev
   start to
   Kotlin MPP
   

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2. Premises
   I want to reuse my knowledge
   I am an Android Dev
   I don’t want to be x-plat
   

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3. 
   What about languages?
   
   

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4. Or actually any other example
   Empire State Building
   Lights Calendar
   App
   

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5. Architecture
   Activity ViewModel
   Repository
   

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6. Libraries
   Repository
   Retrofit
   Gson / Moshi
   

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7. Libraries
   Repository
   Retrofit
   Gson / Moshi
   Ktor
   kotlinx.serializer
   

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8. Modularization
   Activity ViewModel
   Repository
   Native module
   Shared module
   

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9. Modularization
   Repository
   Shared module
   

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11. There is an app a plugin for that.
    PROJECT SETUP
    1
    

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12. Install
    &
    Profit
    

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13. Create
    the project
    

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14. Create
    the project
    

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15. WRITE SOME CODE
    2
    

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16. expect
    actual
    IDE only helps after the directories have
    been created.
    

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17. @Serializable
    data class DayLight(
    val image: String,
    val color: String,
    val reason: String,
    val date: String
    )
    @Serializable
    data class Lights(
    val todayColor: String,
    val picture: String,
    val calendar: List
    )
    :shared
    

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18. class LightRepository {
    private val httpClient = HttpClient {
    install(JsonFeature) {
    val json = Json { ignoreUnknownKeys = true }
    serializer = KotlinxSerializer(json)
    }
    }
    suspend fun getLights() : Lights =
    httpClient.get(LIGHTS_ENDPOINT)
    }
    :shared
    

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19. :android
    class LightsViewModel : ViewModel() {
    private val repository by lazy {
    LightRepository()
    }
    private val _state : MutableLiveData> = MutableLiveData()
    val state : LiveData>
    get() = _state
    fun loadLights() {
    _state.postValue(Lce.Loading)
    viewModelScope.launch {
    try {
    val lights = repository.getLights()
    _state.postValue(Lce.Success(lights))
    } catch(e: Exception) {
    _state.postValue(Lce.Error(e))
    }
    }
    }
    }
    

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20. val state : LiveData>
    get() = _state
    fun loadLights() {
    _state.postValue(Lce.Loading)
    viewModelScope.launch {
    try {
    val lights = repository.getLights()
    _state.postValue(Lce.Success(lights))
    } catch(e: Exception) {
    _state.postValue(Lce.Error(e))
    }
    }
    

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21. They will happen
    WEIRD ERRORS
    3
    

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23. Delete all .iml files in the project
    Close project and IDE
    Delete .idea directory
    Re-import the project
    

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25. upgrade Gradle to 6.7 (KT-43039)
    

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27. bit.ly/KMM-Codelab
    

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28. USE COROUTINES
    4
    

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30. REMEMBER
    You cannot use extension
    functions
    

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31. extension ContentView {
    enum LoadableLights {
    case loading
    case result(Lights)
    case error(String)
    }
    class ViewModel: ObservableObject {
    let repo : LightRepository
    @Published var lights = LoadableLights.loading
    init(repo: LightRepository){
    self.repo = repo
    self.loadLights()
    }
    func loadLights() {
    self.lights = .loading
    repo.getLights(completionHandler: { lights, error in
    if let lights = lights {
    self.lights = .result(lights)
    } else {
    self.lights = .error(error?.localizedDescription ?? "error")
    }
    })
    }
    }
    }
    

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32. self.repo = repo
    self.loadLights()
    }
    func loadLights() {
    self.lights = .loading
    repo.getLights(completionHandler: { lights, error in
    if let lights = lights {
    self.lights = .result(lights)
    } else {
    self.lights = .error(error?.localizedDescription ?? "e
    }
    })
    }
    

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33. private func listView() -> AnyView {
    switch viewModel.lights {
    case .loading:
    return AnyView(Text("Loading...").multilineTextAlignment(.center))
    case .result(let lodableLights):
    return AnyView(LightsView(lights: lodableLights))
    case .error(let description):
    return AnyView(Text(description).multilineTextAlignment(.center))
    }
    }
    

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36. Hello!
    I Am Rob
    Follow me at @_tiwiz
    

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37. Q&A
    

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