For https://stackoverflow.com/questions/59597910

FilteredList.swift

//
//  ContentView.swift
//  Stacketude
//
//  Created by Yonat Sharon on 06/01/2020.
//  Copyright © 2020 Yonat Sharon. All rights reserved.
//

import SwiftUI

struct AirportModel: Identifiable {
    var id = UUID()
    var aptICAO: String
}

class DataManager {
    typealias exit = (([AirportModel]) -> ())
    var airportVector: [AirportModel] = [
        AirportModel(aptICAO: "First"),
        AirportModel(aptICAO: "Second"),
        AirportModel(aptICAO: "Third"),
        AirportModel(aptICAO: "Fourth"),
    ]

    func filter (valoreSearched: String, arrayToSearch: [AirportModel],  closure: @escaping exit)  {
        guard !valoreSearched.isEmpty else {
            closure(arrayToSearch)
            return
        }
        DispatchQueue.global().async {
            let aeroportoFiltrato  = arrayToSearch.filter { $0.aptICAO.localizedCaseInsensitiveContains(valoreSearched) }
            closure(aeroportoFiltrato)
        }
    }
}

struct ContentView: View {
    var dm: DataManager
    @State var searchTerm = ""
    @State var filteredAirports: [AirportModel] = []

    var body: some View {
        VStack {
            TextField("Search", text: $searchTerm, onCommit: updateSearchResults)
                .textFieldStyle(RoundedBorderTextFieldStyle())
                .padding()

            List {
                ForEach(filteredAirports) { valore in
                    Text(valore.aptICAO)
                }
            }
        }
        .onAppear(perform: updateSearchResults)
    }

    func updateSearchResults() {
        dm.filter(valoreSearched: searchTerm, arrayToSearch: dm.airportVector) { airports in
            DispatchQueue.main.async {
                self.filteredAirports = airports
            }
        }
    }
}

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