swift - 在范围 SwiftUI 中找不到 'entity'

Question

我正在尝试将列表中某项的详细信息显示到工作表上。我收到此错误 Cannot find 'entity' in scope 即使它是在详细信息项结构中声明的。

如果工作表位于列表内部，则不会出现此错误，但这会导致仅显示第一个项目的详细信息，即使您选择第一个项目下方的任何其他项目也是如此。

这是一个 macOS 应用。

                @StateObject var vm = CoreDataViewModel()

                  List {
                    ForEach(vm.savedEntites) { entity in
                        Text(entity.name ?? "No Name")
                            .font(.system(size: 25))
                        HStack {
                        Button(action: {vm.deleteMemory(entity: entity)}) {
                                       Label("Delete",systemImage: "trash")
       
                                     }.foregroundColor(Color(.red))
                     
                            Button(action: {showingDetailScreen.toggle()}) {
                            Label("Details", systemImage: "pencil")
                                     }.foregroundColor(Color(.red))                       
                        }                          
                    }// list ends here                
                    .sheet(isPresented: $showingDetailScreen) {
                        DetailItemView(entity: entity,isVisible: self.$showingDetailScreen)
                           }
                }
            

详细项目 View 结构

struct DetailItemView: View  {
        var entity: MemoryEntity
        @Environment(\.presentationMode) var presentationMode
        @Binding var isVisible: Bool
        
 
        var body: some View {
            Text(entity.name ?? "No Name")
            HStack {
            Button("Exit") {
                self.isVisible = false
                   }
            }
            .frame(width: 300, height: 150)
            }
    }

View 模型

class CoreDataViewModel: ObservableObject {
    let container: NSPersistentContainer
    @Published var savedEntites: [MemoryEntity] = []
    @Published var selectedEntity: String = ""
    init() {
        container = NSPersistentContainer(name: "MemoryContainer")
        container.loadPersistentStores { (description, error) in
            if let error = error {
              print("Error loading CoreData. \(error)")
        }
        }
        FetchMemories()
    }
    
    func FetchMemories() {
        let request = NSFetchRequest<MemoryEntity>(entityName: "MemoryEntity")
        do {
        savedEntites = try container.viewContext.fetch(request)
        } catch let error {
            print("Error fetching \(error)")
        }
    }   
   
    }

Answer 1

实体的范围在 ForEach 括号内，

ForEach(vm.savedEntites) { entity in
                                                                                
} //End scope entity var

如果你想在 ForEach 之外显示一个礼物，建议你可以在你的 viewModel 中声明一个 selectedEntity 为@Published

List {
   ForEach(vm.savedEntites) { entity in
   Button(action: {
       vm.selectedEntity = entity
       showingDetailScreen.toggle()
   }) {
}
.sheet(isPresented: $showingDetailScreen) {
   DetailItemView(entity: vm.selectedEntity,isVisible: self.$showingDetailScreen)
}