arrays - 在 swiftui 中编辑现有数组时的持久数据

Question

我试图弄清楚如何使两件事一起工作。第一个是使用 userdefaults 的持久性数据，我通过使用 @Published 和 @Observable 弄清楚了这一点，然后使用 JSONencoder/decoder 来获取要保存的数据，即使在应用程序关闭并重新打开时也是如此。我最近也通过上一个问题了解了第二个问题

我的问题是将两者结合起来。我似乎无法弄清楚如何将下面的代码与预定义的数据数组一起使用，并使用 UserDefaults 使更改持续存在。任何帮助将不胜感激。也许我正在错误地处理这个问题。

通过 UserDefaults 获取持久数据的代码

import SwiftUI

struct CharacterModel: Identifiable, Codable {
    
    var id = UUID()
    var name: String
    var level: Int
    
}

class CharacterViewModel: ObservableObject {
    
    @Published var characters = [CharacterModel]() {
        
        // Write data back to Model
        didSet {
            let encoder =  JSONEncoder()
            
            if let encoded = try?
                encoder.encode(characters) {
                UserDefaults.standard.set(encoded, forKey: "Characters")
            }
        }
    }
    
    init() {
        if let characters = UserDefaults.standard.data(forKey: "Characters") {
            let decoder = JSONDecoder()
            
            if let decoded = try?
                decoder.decode([CharacterModel].self, from: characters) {
                self.characters = decoded
                return
            }
        }
        
        self.characters = []
    }
}

struct DetailView: View {
    
    @Environment(\.presentationMode) var presentationMode
    @ObservedObject var characterVM: CharacterViewModel
    @State private var name = ""
    @State private var level = ""
    
    var body: some View {
        NavigationView {
            Form {
                TextField("Name", text: $name)
                
                TextField("Level", text: $level)
                    .keyboardType(.numberPad)
            }
            .navigationBarTitle("Add Level")
            .navigationBarItems(trailing: Button("Save") {
                if let actualLevel = Int(self.level) {
                    let character = CharacterModel(name: self.name, level: actualLevel)
                    self.characterVM.characters.append(character)
                    self.presentationMode.wrappedValue.dismiss()
                }
            })
        }
    }
}

struct DetailView_Previews: PreviewProvider {
    static var previews: some View {
        DetailView(characterVM: CharacterViewModel())
    }
}

struct Home: View {
    
    @State private var showingAddCharacter = false
    @State var selectedCharacter : CharacterModel!
    @ObservedObject var characterVM = CharacterViewModel()
    
    var body: some View {
        NavigationView {
            List {
                ForEach(characterVM.characters) { char in
                    HStack {
                        VStack(alignment: .leading) {
                            Text(char.name)
                                .font(.headline)
                        
                        }
                        Spacer()
                        Text("\(char.level)")
                    }
                }
                .onDelete(perform: removeItems)
            }

            .navigationBarTitle("Characters")
            .navigationBarItems(trailing:
                Button(action: {
                    self.showingAddCharacter = true
                }) {
                    Image(systemName: "plus")
                }
            )
            .sheet(isPresented: $showingAddCharacter) {
                DetailView(characterVM: self.characterVM)
            }
        }
    }
    
    func removeItems(at offsets: IndexSet) {
        characterVM.characters.remove(atOffsets: offsets)
    }
}

struct Home_Previews: PreviewProvider {
    static var previews: some View {
        Home()
    }
}

编辑预定义数组

class Training: ObservableObject, Identifiable {
    let id: String
    @Published var trainingName: String
    @Published var isRequired: Bool

    init(id: String, trainingName: String, isRequired: Bool) {
        self.id = id
        self.trainingName = trainingName
        self.isRequired = isRequired
    }
} 

class GetTrainings: ObservableObject {
    @Published var items = [Training]()

    init() {
        self.items = [
            Training(id: "ttt1", trainingName: "Safety", isRequired: true),
            Training(id: "ttt2", trainingName: "Administrative", isRequired: false),
            Training(id: "ttt3", trainingName: "Computer", isRequired: true),
            Training(id: "ttt4", trainingName: "People", isRequired: true),
            Training(id: "ttt5", trainingName: "Managerial", isRequired: true),
        ]
    }
}

struct TrainingList: View {

    @ObservedObject var trainings = GetTrainings()

    var body: some View {
        NavigationView {
            VStack {
                List {

                    ForEach(trainings.items) { training in

                        HStack {
                            NavigationLink(destination: TrainingView(training: training)) {
                                Text("\(training.trainingName)")
                            }
                        }
                    }

                }
            }.navigationBarTitle("Training List")
            .onAppear {
                self.trainings.objectWillChange.send() // refresh
            }
        }
    }
}

struct TrainingView: View {

    @ObservedObject var training: Training

    var body: some View {

        VStack {

            Text("\(training.trainingName)").font(.body)
            Text("\(training.isRequired == true ? "Required Training" : "Training Not Required")")

            HStack {
                NavigationLink(destination: EditTraining(training: training)) {
                    Text("Edit Training Details")
                }
            }
        }.navigationBarTitle("\(training.trainingName) Page", displayMode: .inline)

    }
}

struct EditTraining: View {

    @ObservedObject var training: Training

    @State private var newName: String
    @State private var isRequiredTraining: Bool

    init(training: Training) {
        self.training = training
        self._newName = State(initialValue: training.trainingName)
        self._isRequiredTraining = State(initialValue: training.isRequired)
    }

    private func submitData() {

        let newName = self.newName
        let newBoolVal = self.isRequiredTraining

        print("Firebase Sync Id is :\(training.id) Text: \(newName) and Bool: \(newBoolVal)")

        self.training.trainingName = newName
        self.training.isRequired = newBoolVal
    }

    var body: some View {
        VStack {
            Form {
                Section (header: Text("Edit"))  {

                    Text("\(training.trainingName)")
                    /* TextField should Populate With passed In Training Name Here*/
                    TextField("New Name", text: self.$newName)
                    Toggle(isOn: self.$isRequiredTraining) {
                        Text("Is Required")
                    }
                }

                Section {

                    Button(action: {
                        UIApplication.shared.sendAction(#selector(UIResponder.resignFirstResponder),
                            to:nil, from:nil, for:nil)
                        self.submitData()
                    }) {
                        Text("Submit")
                    }

                }
            }
        }.navigationBarTitle("Edit Training Page", displayMode: .inline)
    }
}