打開一個開關并關閉另外兩個

我的申請有問題。我正在嘗試切換一個開關，當這個開關被切換時，所有其他開關都被切換到關閉。我嘗試過使用 onChange 方法。此方法適用于 2 個開關，但不適用于 3 個或更多？

這是我嘗試的代碼：

import SwiftUI
import ToastUI

struct ContentView: View {
@State var generatedNumber : Int = 0

@State var allNumbers : Bool = true
@State var evensOnly : Bool = false
@State var oddsOnly : Bool = false

var body: some View {
    VStack {
        Text("Your genenerated number:")
            .font(.bold(.title)())
        
        Text("\(generatedNumber)")
            .font(.bold(.custom("Generated Number Size", size: 60))())
            .foregroundColor(.cyan)
        
        VStack{
            Toggle("All numbers", isOn: $allNumbers)
                .tint(.cyan)
                .onChange(of: allNumbers) { newValue in
                    //When toggled, turn other switches off, but leave this one on
                    evensOnly = !newValue
                    oddsOnly = !newValue
                }
            Toggle("Even numbers only", isOn: $evensOnly)
                .tint(.cyan)
                .onChange(of: evensOnly) { newValue in
                    allNumbers = !newValue
                    oddsOnly = !newValue
                }
            Toggle("Odd numbers only", isOn: $oddsOnly)
                .tint(.cyan)
                .onChange(of: oddsOnly) { newValue in

                    allNumbers = !newValue
                    evensOnly = !newValue
                }
        }.padding(30)
            .toggleStyle(.switch)
    }
}
}

這就是我得到的：

一次只能打開一個開關，如果切換另一個開關，則關閉另外兩個。執行此操作時的 onChange 方法狀態：“操作嘗試每幀更新多次。” 這是否意味著兩個@State 重新加載試圖在執行時間太接近彼此？請幫我

uj5u.com熱心網友回復：

正如第一條評論已經說過的那樣，您有一個保留周期。為了實作您的目標，有很多解決方案。但是，我會這樣做（參見代碼片段）使用 MVVM 模式來實作它。

struct ContentView: View {
    @State var generatedNumber : Int = 0
    @StateObject var viewModel: ContentViewModel = .init()
    
    var body: some View {
        VStack {
            Text("Your genenerated number:")
                .font(.bold(.title)())
            
            Text("\(generatedNumber)")
                .font(.bold(.custom("Generated Number Size", size: 60))())
                .foregroundColor(.cyan)
            
            VStack {
                Toggle("All numbers", isOn: $viewModel.allNumbers)
                    .tint(.cyan)
                Toggle("Even numbers only", isOn: $viewModel.evensOnly)
                    .tint(.cyan)
                Toggle("Odd numbers only", isOn: $viewModel.oddsOnly)
                    .tint(.cyan)
            }.padding(30)
                .toggleStyle(.switch)
        }
    }
}

class ContentViewModel: ObservableObject {
    @Published var allNumbers : Bool = true
    @Published var evensOnly : Bool = false
    @Published var oddsOnly : Bool = false
    
    private var store: [AnyCancellable] = []
    
    init() {
        $allNumbers
            .sink(receiveValue: {
                guard $0 else { return }
                self.evensOnly = false
                self.oddsOnly = false
            })
            .store(in: &store)

        $evensOnly
            .sink(receiveValue: {
                guard $0 else { return }
                self.allNumbers = false
                self.oddsOnly = false
            })
            .store(in: &store)

        $oddsOnly
            .sink(receiveValue: {
                guard $0 else { return }
                self.allNumbers = false
                self.evensOnly = false
            })
            .store(in: &store)
    }
}

uj5u.com熱心網友回復：

這是一個涉及陣列的稍微健壯的答案，因此現在您有了動態toggle視圖。

enum numbersOptions: String {
                case all = "All numbers"
                case even = "Even numbers"
                case odd = "Odd numbers only"
            }

            struct OptionItem: Identifiable, Equatable {
                let id = UUID()
                let option: numbersOptions
                var isOn: Bool = false
            }

            struct ToggleTest: View {
                @State var generatedNumber : Int = 0
                @State var options = [OptionItem(option: .all, isOn: true), OptionItem(option: .even), OptionItem(option: .odd)]
                
                var body: some View {
                    VStack {
                        Text("Your genenerated number:")
                            .font(.bold(.title)())
                        
                        Text("\(generatedNumber)")
                            .font(.bold(.custom("Generated Number Size", size: 60))())
                            .foregroundColor(.cyan)
                        
                        VStack{
                            ForEach($options) { $option in
                                
                                Toggle(option.option.rawValue, isOn: $option.isOn)
                                    .tint(.cyan)
                                    .onChange(of: option) { updated in

                                        if updated.isOn {
                                            self.options = self.options.map({
                                                var optionItem = $0
                                                optionItem.isOn = $0.id == updated.id
                                                return optionItem })

                                            // ANY UPDATED BASED ON THE SELECTED ITEM

                                            switch updated.option {
                                            case .all:
                                                print("all seleted")
                                            case .even:
                                                print("eve seleted")
                                            case .odd:
                                                print("odd seleted")
                                            }
                                        }
                                    }
                            }
                        }
                        .padding(30)
                        .toggleStyle(.switch)
                    }
                }
            }

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