Question

我需要一个十分钟的人来告诉我为什么我的列表无法通过NavigationLink显示在另一个视图中。我可以看到在“ roadInfo”视图中显示的列表，但里面没有任何内容。不使用navigationLink时，将显示我的列表，没有问题。但是我需要使用navigationLink显示此列表。

在这里，当我选择“ paris-Nord”行时，我通过NavigationLink重定向到一个新视图，但是我的列表为空！（您可以在下一张图片中看到它）

我认为问题是这样的：

    NavigationLink(destination: RoadInfo(depart: self.$Depart, destination: 
    self.$Destination), isActive: self.$hey) {
        EmptyView()
    }

我需要一个NavigationLink才能在我没有选择的另一个视图中显示结果。

有我的代码：

ContentView：

import SwiftUI

struct ContentView: View {

var body: some View {

      NavigationView {

          StationDetail()
         }
     }
 }

     struct ContentView_Previews: PreviewProvider {
          static var previews: some View {
             ContentView()
     }
 }

StationDetail：

 import SwiftUI

 struct StationDetail: View {

 @ObservedObject var webservice = Webservice()
 @State var Depart: String = ""
 @State var Destination: String = ""
 @State var listStation = [Station]()
 @State var predictedValues: Array<String> = []

 @State var isBeingEditedDeparture: Bool = false
 @State var isBeingEditedDestination: Bool = false
 @State var hey: Bool  = false

var body: some View {
    VStack(alignment: .leading){

        NavigationLink(destination: RoadInfo(depart: self.$Depart, destination: self.$Destination), isActive: self.$hey) {
            EmptyView()
        }

        PredictingTextField(listStation: self.$listStation , predictedValues: 
        self.$predictedValues, Depart: self.$Depart, Destination: self.$Destination, 
        isBeingEditedDeparture: self.$isBeingEditedDeparture, isBeingEditedDestination: 
        self.$isBeingEditedDestination )

        .textFieldStyle(RoundedBorderTextFieldStyle())



        List() {

            ForEach(self.predictedValues, id: \.self){ value in

                Text(value)
                    .onTapGesture {
                        if(self.isBeingEditedDeparture == true)
                        {
                            self.Depart = value
                        }
                        else{
                            self.Destination = value
                            self.hey = true
                        }
                }
                }
            }
        }
    }

    struct StationDetail_Previews: PreviewProvider {
    static var previews: some View {
     StationDetail()
    }
    }
  /// TextField capable of making predictions based on provided predictable values
  struct PredictingTextField: View {
  @ObservedObject var webservice = Webservice()
  @Binding var Depart: String
  @Binding var Destination: String
   @Binding var listStation: Array<Station>
   @Binding var predictedValues: Array<String>



@State var predictionInterval: Double?
//@State private var isBeingEdited: Bool = false
@Binding var isBeingEditedDeparture: Bool
@Binding var isBeingEditedDestination: Bool

init(listStation:Binding<[Station]> ,
     predictedValues: Binding<Array<String>>, Depart: Binding<String>, Destination: Binding<String>,isBeingEditedDeparture: Binding<Bool>, isBeingEditedDestination: Binding<Bool>, predictionInterval: Double? = 0.1  ){

    self._listStation = listStation
    self._predictedValues = predictedValues

    self._Depart = Depart
    self._Destination = Destination
    self._isBeingEditedDeparture = isBeingEditedDeparture
    self._isBeingEditedDestination = isBeingEditedDestination
    self.predictionInterval = predictionInterval

 }

var body: some View {
    VStack {

        TextField("Depart", text: $Depart, onEditingChanged: { editing in self.realTimePredictionDeparture(status: editing)}, onCommit: { self.makePrediction()
        })

        TextField("Destination", text: $Destination, onEditingChanged: { editing in self.realTimePredictionDestination(status: editing)}, onCommit: { self.makePrediction()

        })


    }.padding()
}

private func realTimePredictionDeparture(status: Bool){
       self.isBeingEditedDeparture = status
       if status == true {
           Timer.scheduledTimer(withTimeInterval: self.predictionInterval ?? 1, repeats: true) { timer in

               self.makePrediction()


               if self.isBeingEditedDeparture == false {
                   timer.invalidate()
               }
           }
       }
   }

private func realTimePredictionDestination(status: Bool) {
    self.isBeingEditedDestination = status
    if status == true {
        Timer.scheduledTimer(withTimeInterval: self.predictionInterval ?? 1, repeats: true) { timer in

            self.makePrediction()


            if self.isBeingEditedDestination == false {
                timer.invalidate()
            }
        }
    }
}





private func capitalizeFirstLetter(smallString: String) -> String {
    return smallString.prefix(1).capitalized + smallString.dropFirst()

}

private func makePrediction() {
    self.listStation = self.webservice.getStations()
    self.predictedValues = []


    if !self.Depart.isEmpty && self.isBeingEditedDeparture  == true {

        for value in self.listStation{

                if  value.name.contains(self.Depart) || value.name.contains(self.capitalizeFirstLetter(smallString: self.Depart)) {
                    if !self.predictedValues.contains(value.name){
                        self.predictedValues.append(value.name)
                    }
            }
        }
    }

    if !self.Destination.isEmpty && self.isBeingEditedDestination == true {

        for value in self.listStation{

                if  value.name.contains(self.Destination) || value.name.contains(self.capitalizeFirstLetter(smallString: self.Destination)) {
                    if !self.predictedValues.contains(value.name){
                        self.predictedValues.append(value.name)
                    }
             }
        }
    }
}


private func makeMultiPrediction(value: String) {
    for subString in self.Depart.split(separator:" ") {

        if value.contains(String(subString)) || value.contains(self.capitalizeFirstLetter(smallString: String(subString)))
        {
            if !self.predictedValues.contains(value){
                self.predictedValues.append(value)
            }
        }
    }
    for subString in self.Destination.split(separator:" ") {

        if value.contains(String(subString)) || value.contains(self.capitalizeFirstLetter(smallString: String(subString)))
        {
            if !self.predictedValues.contains(value){
                self.predictedValues.append(value)
            }
        }
    }
}
}
}

RoadInfo：

import SwiftUI

struct RoadInfo: View {

@ObservedObject var webservice = Webservice()
@Binding var depart: String
@Binding var destination: String


var body: some View {
    HStack {

      List(){


    ForEach(webservice.rides, id: \.id) {v in
                RowList(connection: v )

        }
         .navigationBarTitle("Trajet")

    }
        .onAppear{
            self.webservice.getConnection(a: self.depart, b: self.destination)
        }


           }
       }
    }

行列表：

   import SwiftUI

   struct RowList: View {

   var connection: Connection


   func convertDate(from connection : String) -> String {
    if let timeInterval = TimeInterval(connection) {
        let date = Date(timeIntervalSince1970: timeInterval)
        let formatter = DateFormatter()
        formatter.dateFormat = "HH:mm"
        return formatter.string(from: date)
    }
    return "" 
}

func convertString(from connection : String) -> String{

    if let range = connection.range(of: "BE.NMBS.") {
        let veh = connection[range.upperBound...]
        return String(veh)
    }
    return "";
}

func convertMinute(from connection : String)-> String {
    let duration: TimeInterval = Double(self.connection.departure.delay)!
    let date = Date()
    let cal = Calendar(identifier: .gregorian)
    let start = cal.startOfDay(for: date)
    let newDate = start.addingTimeInterval(duration)
    let formatter = DateFormatter()
    formatter.dateFormat = "mm"
    let resultString = formatter.string(from: newDate)


        return String("+" + resultString);
 }
func convertMinuteArrival(from connection : String)-> String {
      let duration: TimeInterval = Double(self.connection.arrival.delay)!
      let date = Date()
      let cal = Calendar(identifier: .gregorian)
      let start = cal.startOfDay(for: date)
      let newDate = start.addingTimeInterval(duration)
      let formatter = DateFormatter()
      formatter.dateFormat = "mm"
      let resultString = formatter.string(from: newDate)


          return String("+" + resultString);
   }



var body: some View {

    HStack{
        VStack(alignment: .leading, spacing: 12){

            HStack(spacing: 0){
                Text(convertDate(from: connection.departure.time))
                    .font(.headline)
                //.offset(y: 5)
                 if (connection.departure.delay != "0"){

                    if(Int(connection.departure.delay) ?? 0 >= 600 ){

                        Text(convertMinute(from: connection.departure.delay))
                            .foregroundColor(.red)

                    } else {

                        Text("+" + convertMinute(from: 
                            String(connection.departure.delay)).suffix(1))
                            .foregroundColor(.red)
                    }
                }
            }


            HStack{
                if(connection.departure.platform.count == 2){
                    Text("Quai" + connection.departure.platform)
                        .font(.headline)
                      .foregroundColor(.blue)
                }else
                {
                    Text("Quai " + connection.departure.platform)
                        .font(.headline)
                      .foregroundColor(.blue)
                }
            }

        }
        Spacer()
            .frame(minWidth: 0, maxWidth: 350 )
        VStack {
            if(connection.vias == nil)
            {
                Text("direct")
                .foregroundColor(Color.blue)
                Text(convertString(from: connection.departure.vehicle))
            }
            else{
                ZStack{
                    Image("connection")
                        .frame(width: 40, height: 40 )
                        .cornerRadius(40)
                    Text(connection.vias?.number ?? "" )

                        .foregroundColor(Color.red)
                        .font(.caption)
                      .padding([.leading, .bottom], 40.0)

                }


            }

        //Text(connection.vias?.via[0].vehicle)

    }


        Spacer()
          .frame(minWidth: 0, maxWidth:350 )

        VStack(alignment: .leading, spacing: 12){

            HStack(spacing: 0){

            Text(convertDate(from: connection.arrival.time))


                if(connection.arrival.delay != "0") {
                    if(Int(connection.arrival.delay) ?? 0 >= 600 ){

                        Text(convertMinuteArrival(from: connection.arrival.delay))
                            .foregroundColor(.red)

                    } else {

                        Text("+" + convertMinuteArrival(from: String(connection.arrival.delay)).suffix(1))
                            .foregroundColor(.red)

                    }

                }
            }


            HStack{
                if(connection.arrival.platform.count == 2){
                    Text("Quai" + connection.arrival.platform)
                        .font(.headline)
                        .foregroundColor(.blue)
                }else
                {
                    Text("Quai " + connection.arrival.platform)
                        .font(.headline)
                        .foregroundColor(.blue)
                }
            }
        }


        Spacer()
        }

    }
}

在我的下一个视图中显示列表时出现问题

0 个答案: