多个 ViewModel 中的 @Published 数组 - SwiftUI

问题描述

我的应用程序只有两个视图，两个视图都有自己的 viewmodel。 ViewA 显示和操作来自 selectednumbers 数组的对象。 ViewB 拥有所有可用的对象（数字）——在这个视图中，我想操作被 ViewA 使用的 selectednumbers 数组。

我试图找出如何在这两个 viewmodel 之间共享这些 selectednumbers 数组。我尝试使用 EnvironmentObject、StaticObject 等。但没有任何工作可以满足我的需要。我应该使用什么方法来达到预期的结果。感谢帮助！

import SwiftUI

struct ViewA: View {

    @Observedobject var viewmodel = viewmodelA()

    var body: some View {
        vstack {
            Text("\(viewmodel.number)")
                .font(.largeTitle)
                .padding()
                .onTapGesture {
                    viewmodel.showNext()
                }
            ViewB()
        }
    }
}

class viewmodelA: ObservableObject {
    var numbers: [Int] = []
    @Published var number: Int
    var index = 0

    init() {
        number = numbers.isEmpty ? 0 : numbers[index]
    }

    func showNext() {
        guard !numbers.isEmpty else { return }
        if index < numbers.count - 1 {
            index += 1
        } else {
            index = 0
        }
        number = numbers[index]
    }
}

struct ViewB: View {

    @Observedobject var viewmodel = viewmodelB()

    var body: some View {
        HStack {
            ForEach(viewmodel.numbers,id: \.self) { number in
                Text("\(number)")
                    .foregroundColor(viewmodel.selectednumbers.contains(number) ? .red : .black)
                    .onTapGesture {
                        viewmodel.updateSelection(number)
                    }
            }
        }
    }
}

class viewmodelB: ObservableObject {
    @Published var numbers: [Int] = []
    @Published var selectednumbers: [Int] = []

    init() {
        numbers.append(contentsOf: [1,2,3,4,5,6,7,8])
    }

    func updateSelection(_ number: Int) {
        if selectednumbers.contains(number) {
            selectednumbers.remove(number)
        } else {
            selectednumbers.append(number)
        }
    }
}

extension Array where Element: Equatable {
    mutating func remove(_ object: Element) {
        guard let index = firstIndex(of: object) else {return}
        remove(at: index)
    }
}

解决方法

你仍然可以保持逻辑分离，但你需要保持单一的事实来源，如果你想在视图之间共享数据，你要么需要传递 Bindings 或者您也可以在子视图之间共享 @ObservedObject。

import SwiftUI


struct ViewA: View {

    @ObservedObject var viewModel = ViewModelA(modelB: ViewModelB())

    var body: some View {
        VStack {
            Text("\(viewModel.number)")
                .font(.largeTitle)
                .padding()
                .onTapGesture {
                    viewModel.showNext()
                }
            ViewB(model: viewModel)
        }
    }
}

class ViewModelA: ObservableObject {
    
    var numbers: [Int] = []
    
    @Published var number: Int
    @Published var modelB:ViewModelB
    
    var index = 0

    init(modelB:ViewModelB) {
        self.modelB = modelB
        number = numbers.isEmpty ? 0 : modelB.selectedNumbers[index]
    }

    func showNext() {
        guard !modelB.selectedNumbers.isEmpty else { return }
        if index < modelB.selectedNumbers.count - 1 {
            index += 1
        } else {
            index = 0
        }
        number = modelB.selectedNumbers[index]
    }
}

struct ViewB: View {

    @ObservedObject var model : ViewModelA

    var body: some View {
        HStack {
            ForEach(model.modelB.selectedNumbers,id: \.self) { number in
                Text("\(number)")
                    .foregroundColor(model.modelB.selectedNumbers.contains(number) ? .red : .black)
                    .onTapGesture {
                        model.modelB.updateSelection(number)
                    }
            }
        }
    }
}

struct ViewModelB {
    
    var selectedNumbers: [Int] = []

    init() {
        selectedNumbers.append(contentsOf: [1,2,3,4,5,6,7,8])
    }

   mutating func updateSelection(_ number: Int) {
        if selectedNumbers.contains(number) {
            selectedNumbers.remove(number)
        } else {
            selectedNumbers.append(number)
        }
    }
}

extension Array where Element: Equatable {
    mutating func remove(_ object: Element) {
        guard let index = firstIndex(of: object) else {return}
        remove(at: index)
    }
}