如何使'Published<[String]>.Publisher'符合'RandomAccessCollection'

我正在嘗試根據用戶是否切換收藏按鈕來創建一個更新的視圖。我希望重建整個視圖，以便在更改值陣列時顯示值陣列。在視圖內部，for each 回圈應該顯示陣列中的每個值。

每次更改 savedArray 時我想要更新的視圖是 FavView。但是，當我嘗試使用 foreach 回圈顯示每個值時 saveArray（我將其創建為 @Published 以便視圖可以重建），它給了我錯誤 Generic struct 'ForEach' requires that 'Published<[String]>. Publisher' 符合 'RandomAccessCollection'。我很困惑，因為我認為字串陣列可以用于每個回圈。這不是真的嗎？如何回圈通過 @Published 陣列？謝謝！這是我的 savedArray（在 ViewModel 中）的代碼和我想用 for each 顯示它的 FavView。

final class ViewModel: ObservableObject {
        @Published var items = [Item]()
        @Published var showingFavs = true
        @Published var savedItems: Set<String> = []
        @Published var savedArray: [String]
        // Filter saved items
    
        var filteredItems: [String]  {
            //return self.items
            return savedArray
        }

        var db = Database()
        
        init() {
            self.savedItems = db.load()
            self.items = db.returnList()//the items
            self.savedArray = Array(db.load())
            print("savedarray", savedArray)
            print("important!", self.savedItems, self.items)
        }
        
        func contains(_ item: Item) -> Bool {
                savedItems.contains(item.id)
            }
        
        // Toggle saved items
        func toggleFav(item: Item) {
            print("Toggled!", item)
            if contains(item) {
                savedItems.remove(item.id)
                if let index = savedArray.firstIndex(of: item.id) {
                    savedArray.remove(at: index)
                }
            } else {
                savedItems.insert(item.id)
                savedArray.append(item.id)
            }
            db.save(items: savedItems)
        }
    }

struct FavView: View {
    @StateObject private var vm = ViewModel()
    
    var body: some View {
        VStack {
            
            List {
  
                ForEach($vm.savedArray, id: \.self) { string in
                    let item = vm.db.returnItem(input: string)
                    HStack {
                        VStack(alignment: .leading) {
                            Text(item.title)
                                .font(.headline)
                            
                            Text(item.description)
                                .font(.subheadline)
                        }
                        Spacer()
                        Image(systemName: vm.contains(item) ? "bookmark.fill" : "bookmark")
                            .foregroundColor(.blue)
                            .onTapGesture {
                                vm.toggleFav(item: item)
                            }
                    }
                }//my error is here at the for each
            }
            .cornerRadius(10)
        }
    }
}

//the returnItem function(it's in another file) and accepts a String
    func returnItem(input: String) -> Item{
            let vm = ViewModel()
            let test = cityClass()
            let temp = test.getConvert(input: input)//a datafrime slice
            let state: String = (temp["state", String.self].first ?? "There was an error") ?? "There was an error"
            let zip = ((temp["zip", String.self].first ) ?? "There was an error" ) ?? "There was an error"
            
            let id = input
            let title: String = (temp["primary_city", String.self].first ?? "There was an error") ?? "There was an error"
            let description = "\(state) \(zip)"

        if(vm.contains(Item(id: id, title: title, description: description, isFaved: true)) == false){
            temptList.append(Item(id: id, title: title, description: description, isFaved: true))
        }
        
        print("TEMPLIST", temptList)
            return Item(id: id, title: title, description: description, isFaved: true)
        }

uj5u.com熱心網友回復：

在ForEach，您正在使用$符號來訪問savedArray您必須使用它vm本身

struct FavView: View {
    @StateObject private var vm = ViewModel()
    
    var body: some View {
        VStack {
            
            List {
  
                ForEach($vm.savedArray, id: \.self) { string in //< here $vm.savedArray not vm.$savedArray
                    let item = vm.db.returnItem(input: string)
                    HStack {
                        VStack(alignment: .leading) {
                            Text(item.title)
                                .font(.headline)
                            
                            Text(item.description)
                                .font(.subheadline)
                        }
                        Spacer()
                        Image(systemName: vm.contains(item) ? "bookmark.fill" : "bookmark")
                            .foregroundColor(.blue)
                            .onTapGesture {
                                vm.toggleFav(item: item)
                            }
                    }
                }
            }
            .cornerRadius(10)
        }
    }
}

這應該有效。

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