SwiftUI编辑Core Data关联Pause实体后DetailView UI不更新求助

场景与问题 #

• 基于SwiftUI和Core Data开发应用，WorkingDay与Pause为一对多关系
• DetailView展示WorkingDay详情及关联的Pause列表，通过模态视图编辑两者的时间属性
• 核心问题：编辑Pause实体的开始/结束时间后，Core Data数据已保存，但DetailView的Pause列表不会立即更新；编辑WorkingDay自身属性时UI却能正常刷新

相关代码 #

DetailView #

struct DetailView: View {
    @Environment(\.dismiss) var dismiss
    @StateObject var viewModel: ViewModel

    var body: some View {
        VStack {
            List {
                Section("Pauses") {
                    ForEach(viewModel.model.arrPause, id: \.self) { pause in
                        HStack {
                            Text("Start: \(pause.wrappedStartPause.formatted(date: .omitted, time: .standard))")
                            Text("Finish: \(pause.wrappedFinishPause.formatted(date: .omitted, time: .standard))")
                        }
                    }
                }
            }
        }
        .onAppear {
            viewModel.calculatedWorkingTime()
        }
        .sheet(isPresented: $viewModel.onChange) {
            EditSheet(viewModel: viewModel)
        }
    }
    
    init(model: WorkingDay, persistenceController: PersistenceController) {
        _viewModel = StateObject(wrappedValue: ViewModel(model: model, persistenceController: PersistenceController.shared))
    }
}

ViewModel #

class ViewModel: ObservableObject {
    @Published var model: WorkingDay
    @Published var selectedPause: Pause?
    @Published var onChange: Bool = false

    private let persistenceController: PersistenceController

    init(model: WorkingDay, persistenceController: PersistenceController) {
        self.model = model
        self.persistenceController = persistenceController
    }

    func update() {
        if let selectedPause {
            selectedPause.startPause = ... // 更新后的时间值
            selectedPause.finishPause = ...
        }

        model.objectWillChange.send()
        persistenceController.save()
    }
}

已尝试方案 #

• 为WorkingDay配置NSFetchedResultsController：未监听Pause实体，无法触发刷新
• 调用WorkingDay的objectWillChange.send()：编辑Pause后调用无效
• 为List添加.id(UUID())：强制重载但会重建整个视图层级，非理想方案
• 手动重新获取WorkingDay：未解决问题

解决方案 #

方案1：手动触发Pause及关联集合的变更通知 #

Core Data的NSManagedObject默认不会自动向SwiftUI发送变更通知，需手动触发。修改ViewModel的update方法：

func update() {
    if let selectedPause {
        selectedPause.objectWillChange.send() // 触发单个Pause的变更通知
        selectedPause.startPause = ... // 更新值
        selectedPause.finishPause = ...
        
        model.arrPause.objectWillChange.send() // 触发WorkingDay关联集合的变更通知
    }

    model.objectWillChange.send()
    persistenceController.save()
}

方案2：用@FetchRequest直接获取关联Pause（推荐） #

在DetailView中通过@FetchRequest获取当前WorkingDay关联的所有Pause，让Core Data自动监听变更并刷新UI：

struct DetailView: View {
    @Environment(\.dismiss) var dismiss
    @StateObject var viewModel: ViewModel
    @FetchRequest var pauses: FetchedResults<Pause>

    var body: some View {
        VStack {
            List {
                Section("Pauses") {
                    ForEach(pauses, id: \.self) { pause in
                        HStack {
                            Text("Start: \(pause.wrappedStartPause.formatted(date: .omitted, time: .standard))")
                            Text("Finish: \(pause.wrappedFinishPause.formatted(date: .omitted, time: .standard))")
                        }
                    }
                }
            }
        }
        .onAppear {
            viewModel.calculatedWorkingTime()
        }
        .sheet(isPresented: $viewModel.onChange) {
            EditSheet(viewModel: viewModel)
        }
    }

    init(model: WorkingDay, persistenceController: PersistenceController) {
        _viewModel = StateObject(wrappedValue: ViewModel(model: model, persistenceController: PersistenceController.shared))
        // 初始化FetchRequest，筛选当前WorkingDay关联的Pause
        _pauses = FetchRequest(
            entity: Pause.entity(),
            sortDescriptors: [NSSortDescriptor(keyPath: \Pause.startPause, ascending: true)],
            predicate: NSPredicate(format: "workingDay == %@", model)
        )
    }
}

方案3：确保Core Data关系配置正确 #

检查WorkingDay与Pause的实体关系是否设置了反向关系，且WorkingDay的arrPause属性为默认的Dynamic类型。Core Data会自动管理反向关系的变更传播，确保关联集合的变更能被SwiftUI捕获。

内容的提问来源于stack exchange，提问作者brusherr