@State 未在 SwiftUI 2 中更新 [英] @State not updating in SwiftUI 2

问题描述

有人在 Xcode 12b 的 SwiftUI 2 中看到 @State 变量没有更新的问题吗?问题代码在 contextMenu 按钮中.

Anybody see problems with @State variables not updating in SwiftUI 2 in Xcode 12b? The problem code is in the contextMenu buttons.

showSheet 变量切换为 true，但 sheetItem 值未更改.相同的代码适用于 SwiftUI 1.

The showSheet var is toggled to true but the sheetItem value is not changed. This same code worked in SwiftUI 1.

我已经提交了反馈，但想知道是否有其他人看到过这个问题.

I have filed a Feedback, but was wondering if anyone else has seen this problem.

完整代码:

struct ConnectionsView: View {

@EnvironmentObject var connectionViewModel : FileDataViewModel<Connection>

@State private var editMode = EditMode.inactive
@State private var importedConnections = false
@State private var showEditSheet = false
@State private var selectedIndex = 0
@State private var showSheet = false
@State private var sheetItem = SheetItem.openFile //TOD: Set back to .none when ButtonActions fixed
@State private var newConnection = Connection()

var body : some View {
    NavigationView {
        List {
            ForEach(connectionViewModel.items) { connection in
                NavigationLink (destination: SSHSessionView (connection: connection)) {
                    ConnectionView(connection: connection)
                        //pass tap through the view to allow the NavigationLink to work
                        .allowsHitTesting(self.editMode == .inactive ? false : true)
                        .onTapGesture {
                            if self.editMode.isEditing {
                                self.selectedIndex = self.connectionViewModel.items.firstIndex(where: {$0.id == connection.id})!
                                self.sheetItem = .editItem
                                self.showSheet.toggle()
                            }
                        }
                }
            }
            .onDelete(perform: deleteItem)
            .onMove(perform: moveItem)
        }
        .onAppear {
            UITableView.appearance().tableFooterView = UIView()
        }
        .navigationBarTitle("Connections", displayMode: .large)
        .navigationBarItems(
            leading:
                EditButton()
                    .hoverWithPaddingModifier(),
            trailing:
                Button(action: {
                }, label: {
                    Image(systemName: "plus")
                })
                .contextMenu {
                    Button("New Connections file...", action: {
                        sheetItem = .newFile
                        showSheet.toggle()
                    })
                    Button("Open Connections file...", action: {
                        sheetItem = .openFile
                        showSheet = true
                    })
                    if connectionViewModel.fileOpened {
                        Button("New Connection", action: {
                            sheetItem = .newItem
                            showSheet.toggle()
                        })
                    }
                }
        )
            
        .environment(\.editMode, $editMode)
        
        .sheet(isPresented: $showSheet, content: {
            
            if self.sheetItem == .editItem {
                AddEditConnectionView (connection: self.$connectionViewModel.items[self.selectedIndex], newConnection: false)
                    .environmentObject(self.connectionViewModel)
            }
            
            if self.sheetItem == .newFile {
                FilePickerView(callback : self.importedConnections == false ? self.pickedDocuments : self.newDocFromServerList, UTIs : connectionUTIs, newFileURL : FileDataViewModel<Connection>.getBlankFile (fileType : ViewTypes.connections)!)
            }
            
            if self.sheetItem == .openFile {
                FilePickerView(callback : self.pickedDocuments, UTIs : connectionUTIs, newFileURL: nil)
            }

            if self.sheetItem == .newItem {
                AddEditConnectionView (connection: self.$newConnection, newConnection: true)
                    .environmentObject(self.connectionViewModel)
            }
        })
    }
}

推荐答案

现在已经晚了，但它会帮助面临同样问题的其他人.使用@Binding 变量代替@State.

It's late but it will help others who are facing the same issue. Use @Binding variable instead of @State.

struct CarListView: View {
    @State var isPresented = false
    @State var selectedCar: Car?

    var body: some View {
        Button(action: {
            self.selectedCar = cars[selectedIndex]
            self.isPresented.toggle()
        }) {
            Text("Test")
        }
        .sheet(isPresented: self.$isPresented) {
            WorkoutDetails(workout: selectedCar)
        }
    }
}

struct CarDetailsView: View {
    @Binding var selectedCar: Car?
    // Set a Binding instead of the @State variable
    // If you not pass @Binding then you will not get updated variable here

    var body: some View {
        VStack {
            // your code
        }
    }
}

这篇关于@State 未在 SwiftUI 2 中更新的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！