轻糖的 KMP 渐进式迁移实践（三）：KMPObservableViewModel 直连，iOS 本地 ViewModel 全量退休

// OnboardingStateHolder.swift —— 第二篇的形态
@MainActor
final class OnboardingStateHolder: ObservableObject {
    @Published var state: HomeUiState = .init()
    private let viewModel = Shared.OnboardingViewModel()
    private var collectionTask: Task<Void, Never>?

    func startObserving() {
        collectionTask = Task { [weak self] in
            for await state in self?.viewModel.uiState ?? AsyncStream<HomeUiState>.empty {
                guard let self else { return }
                self.state = state
            }
        }
        viewModel.loadData()
    }

    deinit {
        collectionTask?.cancel()
    }
}

[versions]
androidx-viewmodel = "2.10.0"
kmp-observableviewmodel = "1.0.5"
kmp-nativecoroutines = "1.0.4"

[libraries]
androidx-lifecycle-viewmodel = { module = "androidx.lifecycle:lifecycle-viewmodel", version.ref = "androidx-viewmodel" }
kmp-observableviewmodel-core = { module = "com.rickclephas.kmp:kmp-observableviewmodel-core", version.ref = "kmp-observableviewmodel" }

[plugins]
kmp-nativecoroutines = { id = "com.rickclephas.kmp.nativecoroutines", version.ref = "kmp-nativecoroutines" }

plugins {
    alias(libs.plugins.kmp.nativecoroutines)
    // ...
}

kotlin {
    listOf(iosArm64(), iosSimulatorArm64()).forEach { iosTarget ->
        iosTarget.binaries.framework {
            baseName = "Shared"
            isStatic = true
            export(libs.androidx.lifecycle.viewmodel)        // 导出给 iOS 可见
            export(libs.kmp.observableviewmodel.core)
        }
    }

    sourceSets {
        commonMain.dependencies {
            api(libs.androidx.lifecycle.viewmodel)
            api(libs.kmp.observableviewmodel.core)
            // ...
        }
    }
}

// 不暴露 NativeCoroutines 生成的中间类型，Swift 侧只看得到注解后的干净 API
nativeCoroutines {
    exposedSeverity = ExposedSeverity.NONE
}

// Extensions/KMPObservableViewModel.swift
import KMPObservableViewModelCore
import Shared

extension Shared.ViewModel: @retroactive KMPObservableViewModelCore.ViewModel { }

// 改造前：androidx ViewModel + 普通 MutableStateFlow
class HomeViewModel : androidx.lifecycle.ViewModel() {
    private val _uiState = MutableStateFlow(HomeUiState())
    val uiState: StateFlow<HomeUiState> = _uiState.asStateFlow()
    // iOS 侧只能靠 SKIE 转 AsyncSequence + StateHolder 手动订阅
}

// 改造后：KMP-ObservableViewModel + @NativeCoroutinesState
import com.rickclephas.kmp.nativecoroutines.NativeCoroutinesState
import com.rickclephas.kmp.observableviewmodel.MutableStateFlow
import com.rickclephas.kmp.observableviewmodel.ViewModel
import com.rickclephas.kmp.observableviewmodel.launch

class HomeViewModel : ViewModel() {
    // 关键：必须用 observableviewmodel 的 MutableStateFlow(viewModelScope, initial)
    private val _uiState = MutableStateFlow(viewModelScope, HomeUiState())

    @NativeCoroutinesState
    val uiState: StateFlow<HomeUiState> = _uiState.asStateFlow()

    init {
        startObserving()  // viewModelScope.launch { ... }
    }

    fun loadData() {
        viewModelScope.launch { /* 业务逻辑 */ }
    }
}

import SwiftUI
@preconcurrency import Shared
@preconcurrency import KMPObservableViewModelSwiftUI

struct FoodDetailView: View {
    // @StateViewModel 替代 @StateObject，直接持有 KMP ViewModel
    @StateViewModel private var viewModel = Shared.FoodDetailViewModel()

    var body: some View {
        Text("\(viewModel.uiState.foodName)")
        // ...
    }
    .task {
        try? await viewModel.loadData()  // suspend fun → async throws
    }
}

// AuthSignInHelper.swift —— 平台层 Sign-In SDK 的唯一职责
enum AuthSignInHelper {
    /// Google SDK 交互拿 idToken（需 present VC）
    @MainActor
    static func googleIdToken(presenting viewController: UIViewController) async throws -> String {
        let result = try await GIDSignIn.sharedInstance.signIn(withPresenting: viewController)
        guard let idToken = result.user.idToken?.tokenString else {
            throw AuthError.accountInvalid
        }
        return idToken
    }

    /// 从 Apple 授权结果解析 idToken
    static func appleIdToken(from result: Result<ASAuthorization, Error>) throws -> String {
        // ...
        return idToken
    }
}

// shared/iosMain —— KMP 侧定义桥接协议
interface HealthKitBridgeDelegate {
    fun isAvailable(): Boolean
    suspend fun checkAuthorizationStatus(): HealthDataAuthorizationStatus
    suspend fun requestAuthorization(): Boolean
    suspend fun readBloodGlucoseRecords(startTime: Instant, endTime: Instant, uid: String): List<BloodSugarRecord>
}

// HealthKitBridgeSetup.swift —— Swift 实现 KMP 协议
final class HealthKitBridgeDelegateImpl: HealthKitBridgeDelegate {
    func isAvailable() -> Bool {
        MainActor.assumeIsolated {
            HealthKitRepository.shared.isHealthKitAvailable
        }
    }

    func __readBloodGlucoseRecords(
        startTime: KotlinInstant,
        endTime: KotlinInstant,
        uid: String
    ) async throws -> [Shared.BloodSugarRecord] {
        let repository = await HealthKitRepository.shared
        let startDate = Date(timeIntervalSince1970: TimeInterval(startTime.epochSeconds))
        let endDate = Date(timeIntervalSince1970: TimeInterval(endTime.epochSeconds))
        let records = try await repository.importBloodGlucoseRecords(from: startDate, to: endDate, uid: uid)
        return records.map { $0.toKmpModel() }  // 本地 Swift 模型 → KMP model
    }
}

data class TimelineEventDto(
    val id: String,
    val timestamp: Instant,
    /** [timestamp] 的 epoch 毫秒，供 Swift / ObjC 直接消费 */
    val timestampEpochMillis: Long,
    val type: TimelineEventType,
    // ...
)

data class HomeUiState(
    val selectedDateEpochMillis: Long = Clock.System.now().toEpochMilliseconds(),
    val bloodSugarUnitIsMgDl: Boolean = false,      // 枚举旁路布尔
    val selectedTimeRangeOrdinal: Int = 0,          // 枚举旁路序数
    val timelineEvents: List<TimelineEventDto> = emptyList(),
    // ...
)

class AICreditViewModel : ViewModel() {
    /** 自动刷新最小间隔：避免视图重建/导航切换时产生冗余请求 */
    private val minRefreshIntervalMs = 30_000L
    private var lastCreditRefreshAtMs = 0L

    private fun shouldSkipAutoRefresh(lastRefreshAtMs: Long): Boolean {
        val now = Clock.System.now().toEpochMilliseconds()
        return now - lastRefreshAtMs < minRefreshIntervalMs
    }

    suspend fun refreshCredit(force: Boolean = false) {
        val uid = currentUserId() ?: return
        if (!force && shouldSkipAutoRefresh(lastCreditRefreshAtMs)) return
        // ...
    }
}

// shared/src/commonMain/.../viewmodel/StatisticsReportViewModel.kt
data class StatisticsReportUiState(
    val isLoading: Boolean = true,
    val period: ReportPeriod = ReportPeriod.preset(ReportPeriodPreset.default),
    val report: StatisticsReport? = null,
    val isComparisonMode: Boolean = false,
    val isLoggedIn: Boolean = false,
    val isPremium: Boolean = false,
    val errorMessage: String? = null,
)

class StatisticsReportViewModel : ViewModel() {
    private val _uiState = MutableStateFlow(viewModelScope, StatisticsReportUiState())
    @NativeCoroutinesState
    val uiState: StateFlow<StatisticsReportUiState> = _uiState.asStateFlow()

    init { refresh() }

    fun selectPeriod(preset: ReportPeriodPreset) {
        if (preset == ReportPeriodPreset.CUSTOM) return
        _uiState.update { it.copy(period = ReportPeriod.preset(preset), errorMessage = null) }
        refresh()
    }
    // ...
}

// iosApp/.../Views/Profile/StatisticsReportView.swift
struct StatisticsReportView: View {
    @StateViewModel private var viewModel = StatisticsReportViewModel()
    // 纯 UI：渲染 viewModel.uiState，回调 viewModel.selectPeriod(...)
}

// androidApp/.../ui/screens/profile/StatisticsReportScreen.kt
@Composable
fun StatisticsReportScreen(viewModel: StatisticsReportViewModel = viewModel()) {
    val uiState by viewModel.uiState.collectAsStateWithLifecycle()
    // 纯 UI：渲染 uiState，回调 viewModel.selectPeriod(...)
}