SwiftUI 列表未使用 ForEach 正确更新

Question

我正在尝试使用带有两个 ForEach 循环的列表来创建收藏夹功能。当我点击按钮时，项目移动到正确的部分，但按钮图像和功能没有更新。有没有我遗漏或做错了什么？

如果我导航到另一个视图并返回，最初会正确呈现列表，但如果我单击按钮仍会表现出相同的行为。

如果我使用两个具有完全相同设置的单独列表，一切正常，但在 UI 中看起来很奇怪，因为即使列表中没有任何项目，每个列表也会占用相同的空间列表。

或者，有没有办法在点击按钮时强制重绘列表？

谢谢！

import SwiftUI

struct BusinessListView: View {

    @EnvironmentObject var state: ApplicationState

    var body: some View {
        VStack{

            List {
                Section(header: Text("Favorites")) {

                    if(state.favorites.count == 0){

                        Text("No Favorites")
                    }
                    else {
                        ForEach(state.favorites, id: \.self) { favorite in
                            HStack{
                                Button(
                                    action: {},
                                    label: { Image(systemName: "heart.fill").foregroundColor(.red) }
                                )
                                    .onTapGesture { self.toggleFavorite(business: favorite)}
                                Text("\(favorite.name)")
                            }
                        }
                    }
                }

                Section(header: Text("Other Businesses")) {
                    ForEach(state.others, id: \.self) { business in
                        HStack{
                            Button(
                                action: {},
                                label: { Image(systemName: "heart") }
                            )
                                .onTapGesture { self.toggleFavorite(business: business)}
                            Text("\(business.name)")
                        }
                    }
                }
            }
        }
    }

    func toggleFavorite(business: Business){

        if(state.favorites.contains(business)){

            self.state.favorites = self.state.favorites.filter {[=10=] != business}

            self.state.others.append(business)
        }
        else{

            self.state.others = self.state.others.filter {[=10=] != business}

            self.state.favorites.append(business)
        }

        sortBusinesses()
    }


    func sortBusinesses(){

        self.state.favorites.sort {
            [=10=].name < .name
        }

        self.state.others.sort {
            [=10=].name < .name
        }
    }
}

Answer 1

您是否已确认正在调用 .onTapGesture？或者，您可以将 self.toggleFavorite(business: favorite) 放在按钮的操作内。

                            Button(
                                action: { self.toggleFavorite(business: business) },
                                label: { Image(systemName: "heart") }
                            )

Answer 2

更新的答案，有效，但是...

1) 诀窍是每当您将 "cell" 从收藏夹更改为 non-favorite 时更改 id -> 我假设 Apple 使用 UITableView - dequeueResubleCell 的逻辑，如果 id 相同不会更新，只是 reused/copied 所以心没有变

2) 我现在在收藏夹更改时随机更改 ID - 你必须在那里考虑 better/cleaner 解决方案。

struct BusinessListView: View {

    @EnvironmentObject var state: ApplicationState

    var body: some View {
        VStack{

            List {
                Section(header: Text("Favorites")) {

                    if(state.favorites.count == 0){

                        Text("No Favorites")
                    }
                    else {
                        ForEach(state.favorites, id: \.self) { favorite in
                            HStack{
                                Button(
                                    action: {
                                        self.toggleFavorite(business: favorite)
                                },
                                    label: {
                                        HStack {
                                            Image(systemName: "heart.fill").foregroundColor(.red)
                                            Text("\(favorite.name)")
                                        }
                                }
                                ).id(favorite.id)
                            }
                        }
                    }
                }

                Section(header: Text("Other Businesses")) {
                    ForEach(state.others, id: \.self) { business in
                        HStack{
                            Button(
                                action: {
                                    self.toggleFavorite(business: business)
                            },
                                label: {
                                    HStack {
                                        Image(systemName: "heart")
                                        Text("\(business.name)")
                                    }
                            }
                            )
                            .id(business.id)
                        }
                    }
                }
            }
        }
    }

    func toggleFavorite(business: Business){

        if(state.favorites.contains(business)){

            self.state.favorites = self.state.favorites.filter {[=10=] != business}

            self.state.others.append(business)

            if let index = self.state.others.index(of: business) {
                self.state.others[index].id = Int.random(in: 10000...50000)
            }
        }
        else{

            self.state.others = self.state.others.filter {[=10=] != business}

            self.state.favorites.append(business)

            if let index = self.state.favorites.index(of: business) {
                self.state.favorites[index].id = Int.random(in: 10000...50000)
            }
        }

        sortBusinesses()
    }


    func sortBusinesses(){

        self.state.favorites.sort {
            [=10=].name < .name
        }

        self.state.others.sort {
            [=10=].name < .name
        }
    }
}

SwiftUI 列表未使用 ForEach 正确更新

SwiftUI List Not Updating Correctly with ForEach

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swiftui-list