Change State with DocumentPicker SwiftUI - view

Question

I'm trying to get a List View to appear after selecting a document with documentPicker. Getting the following error...
Fatal error: No ObservableObject of type Switcher found.
A View.environmentObject(_:) for Switcher may be missing as an ancestor of this view.: file /BuildRoot/Library/Caches/com.apple.xbs/Sources/Monoceros/Monoceros-30.4/Core/EnvironmentObject.swift, line 55
It seems like I should use an EnviromentObject binding to have all views be able to read, access and update the Switcher class. Under the Coordinator Class in CSVDocumentPicker.swift is where things seem to go wrong.
I'm using #EnvironmentObject var switcher:Switcher and using the documentPicker function to toggle the switcher state so the Lists View will be displayed. I'm stumped.
SceneDelegate.swift
import UIKit
import SwiftUI
class SceneDelegate: UIResponder, UIWindowSceneDelegate {
var window: UIWindow?
var switcher = Switcher()
func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
let contentView = ContentView().environmentObject(Switcher())
if let windowScene = scene as? UIWindowScene {
let window = UIWindow(windowScene: windowScene)
window.rootViewController = UIHostingController(rootView: contentView.environmentObject(switcher))
self.window = window
window.makeKeyAndVisible()
}
}
func sceneDidDisconnect(_ scene: UIScene) {
}
func sceneDidBecomeActive(_ scene: UIScene) {
}
func sceneWillResignActive(_ scene: UIScene) {
}
func sceneWillEnterForeground(_ scene: UIScene) {
}
func sceneDidEnterBackground(_ scene: UIScene) {
}
}
CSVDocumentPicker.swift
import Combine
import SwiftUI
class Switcher: ObservableObject {
var didChange = PassthroughSubject<Bool, Never>()
var isEnabled = false {
didSet {
didChange.send(self.isEnabled)
}
}
}
struct CSVDocumentPicker: View {
#EnvironmentObject var switcher:Switcher
#State private var isPresented = false
var body: some View {
VStack{
Text("csvSearch")
Button(action: {self.isPresented = true
})
{Text("import")
Image(systemName: "folder").scaledToFit()
}.sheet(isPresented: $isPresented) {
() -> DocumentPickerViewController in
DocumentPickerViewController.init(onDismiss: {
self.isPresented = false
})
}
if switcher.isEnabled {
ListView()
}
}
}
}
struct CSVDocumentPicker_Previews: PreviewProvider {
static var previews: some View {
CSVDocumentPicker().environmentObject(Switcher())
}
}
/// Wrapper around the `UIDocumentPickerViewController`.
struct DocumentPickerViewController {
private let supportedTypes: [String] = ["public.item"]
// Callback to be executed when users close the document picker.
private let onDismiss: () -> Void
init(onDismiss: #escaping () -> Void) {
self.onDismiss = onDismiss
}
}
// MARK: - UIViewControllerRepresentable
extension DocumentPickerViewController: UIViewControllerRepresentable {
typealias UIViewControllerType = UIDocumentPickerViewController
func makeUIViewController(context: Context) -> DocumentPickerViewController.UIViewControllerType {
let documentPickerController = UIDocumentPickerViewController(documentTypes: supportedTypes, in: .import)
documentPickerController.allowsMultipleSelection = false
documentPickerController.delegate = context.coordinator
return documentPickerController
}
func updateUIViewController(_ uiViewController: DocumentPickerViewController.UIViewControllerType, context: Context) {}
// MARK: Coordinator
func makeCoordinator() -> Coordinator {
Coordinator(self)
}
class Coordinator: NSObject, UIDocumentPickerDelegate, ObservableObject {
#EnvironmentObject var switcher:Switcher
var parent: DocumentPickerViewController
init(_ documentPickerController: DocumentPickerViewController) {
parent = documentPickerController
}
func documentPicker(_ controller: UIDocumentPickerViewController, didPickDocumentAt url: URL) {
globalPathToCsv = url
loadCSV()
switcher.isEnabled.toggle()
}
func documentPickerWasCancelled(_ controller: UIDocumentPickerViewController) {
parent.onDismiss()
}
}
}
ContentView.swift
import SwiftUI
import UIKit
var globalPathToCsv:URL!
var csvArray = [[String:String]]()
var csv = CSVaccessability()
func loadCSV(){
csv.csvToList()
// print(csvArray)
}
struct ContentView: View {
#EnvironmentObject var switcher:Switcher
var body: some View {
VStack{
CSVDocumentPicker().environmentObject(Switcher())
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView().environmentObject(Switcher())
}
}
ListView.swift
import SwiftUI
struct ListView: View {
var body: some View {
HStack{
List {
ForEach(csvArray, id:\.self) { dict in Section {DataList(dict: dict)} }
}
}}
}
struct DataList : View {
#State var dict = [String: String]()
var body: some View {
let keys = dict.map{$0.key}
let values = dict.map {$0.value}
return ForEach(keys.indices) {index in
HStack {
Text(keys[index])
Text("\(values[index])")
}
}
}
}
struct ListView_Previews: PreviewProvider {
static var previews: some View {
ListView()
}
}
CSVaccessability.swift
import Foundation
import SwiftCSV
var csvData:[[String]]!
var headers:[String] = []
class CSVaccessability {
var numberOfColumns:Int!
var masterList = [[String:Any]]()
func csvToList(){
if let url = globalPathToCsv {
do {
print(url)
let csvFile: CSV = try CSV(url: globalPathToCsv)
let csv = csvFile
//print(stream)
//print(csvFile)
headers = csv.header
csvArray=csv.namedRows
} catch {print("contents could not be loaded")}}
else {print("the URL was bad!")}
}
}
I've imported SwiftCSV for this project...

Answer 1

Created a new class...
ToggleView.swift
import Foundation
class ToggleView: ObservableObject {
#Published var toggleView: Bool = false
}
Added the Environment Object to ContentView.swift
#EnvironmentObject var viewToggle: ToggleView
Also added .environmentObject(ToggleView()) to any view that would be called and cause a crash the crash logs helped with this...
Text("csvSearch")
Button(action: {self.isPresented = true
self.viewToggle.toggleView.toggle()
// self.switcher = true
})
{Text("import")
Image(systemName: "folder").scaledToFit()
}.sheet(isPresented: $isPresented) {
() -> DocumentPickerViewController in
DocumentPickerViewController.init()
}
if self.picker {
DocumentPickerViewController().environmentObject(ToggleView())
}
if self.viewToggle.toggleView{
ListView()
}
}
}
}

Answer 2

Did you ever get this working? The only problem I found was with the line var csv = CSVaccessability() in the ContentView. CSVaccessability does not exist.

Answer 3

This is my solution for the Catalyst app for Mac, but to avoid pressing theImage (systemName: "book")button a second time to update the data in the text fields, I have implemented a hidden view in GeoFolderReadFileView to force the view update.
//File: GeoFolderCodStruct
import Foundation
struct GeoFolderCodStruct:Codable {
var isActive:Bool = true
var dataCreazione:Date = Date()
var geoFolderPath:String = ""
var nomeCartella:String = ""
var nomeCommittente:String = ""
var nomeArchivio:String = ""
var note:String = ""
var latitudine:Double? = nil
var longitudine:Double? = nil
var radiusCircle:Int16? = nil
//Roma 42.1234 13.1234
}
//File: PickerForReadFile
import SwiftUI
final class PickerForReadFile: NSObject, UIViewControllerRepresentable, ObservableObject {
#Published var geoFolder = GeoFolderCodStruct()
lazy var viewController:UIDocumentPickerViewController = {
let vc = UIDocumentPickerViewController(documentTypes: ["geof"], in: .open)
vc.allowsMultipleSelection = false
vc.delegate = self
return vc
}()
func makeUIViewController(context: UIViewControllerRepresentableContext<PickerForReadFile>) -> UIDocumentPickerViewController {
viewController.delegate = self
return viewController
}
func updateUIViewController(_ uiViewController: UIDocumentPickerViewController, context: UIViewControllerRepresentableContext<PickerForReadFile>) {
print("updateUIViewController")
}
}
extension PickerForReadFile: UIDocumentPickerDelegate {
func documentPicker(_ controller: UIDocumentPickerViewController, didPickDocumentsAt urls: [URL]) {
if urls.count > 0 {
DispatchQueue.main.async {
let url = urls[0]
do {
let data = try Data(contentsOf: url)
let decoder = JSONDecoder()
decoder.dateDecodingStrategy = .formatted(dateFormatter)
let jsonData = try decoder.decode(GeoFolderCodStruct.self, from: data)
self.geoFolder = jsonData
print("geoFolder: \(self.geoFolder.nomeArchivio)")
} catch {
print("error:\(error)")
}
}
}
}
func documentPickerWasCancelled(_ controller: UIDocumentPickerViewController) {
controller.dismiss(animated: true) {
print("Cancel from picker view controller")
}
}
}
//File: GeoFolderReadFileView
import SwiftUI
struct GeoFolderReadFileView: View {
#ObservedObject var picker = PickerForReadFile()
#Binding var geoFolder: GeoFolderCodStruct
var body: some View {
VStack(alignment: .trailing){
Button(action: {
#if targetEnvironment(macCatalyst)
print("Press open file")
let vc = UIApplication.shared.windows[0].rootViewController!
vc.present(self.picker.viewController, animated: true) {
self.geoFolder = self.picker.geoFolder
}
#endif
}) {
Image(systemName: "book")
}
urlPickedView()
.hidden()
}
}
private func urlPickedView() -> some View {
DispatchQueue.main.async {
let geoF = self.picker.geoFolder
print("Committente: \(geoF.nomeCommittente) - Archivio: \(geoF.nomeArchivio)")
self.geoFolder = geoF
}
return TextField("", text: $geoFolder.geoFolderPath)
}
}
//File: ContentView
import SwiftUI
struct ContentView: View {
#State private var geoFolder = GeoFolderCodStruct()
var body: some View {
VStack {
HStack {
Text("Open GeoFolder File:")
.padding()
Spacer()
GeoFolderReadFileView(geoFolder: $geoFolder)
.padding()
}
.padding()
Group {
TextField("", text: $geoFolder.geoFolderPath)
.textFieldStyle(RoundedBorderTextFieldStyle())
.padding()
TextField("", text: $geoFolder.nomeCartella)
.textFieldStyle(RoundedBorderTextFieldStyle())
.padding()
TextField("", text: $geoFolder.nomeCommittente)
.textFieldStyle(RoundedBorderTextFieldStyle())
.padding()
TextField("", text: $geoFolder.nomeArchivio)
.textFieldStyle(RoundedBorderTextFieldStyle())
.padding()
TextField("", text: $geoFolder.note)
.textFieldStyle(RoundedBorderTextFieldStyle())
.padding()
}
.padding()
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
and the last, the json file to read for test the code.
{
"nomeCommittente" : "Appple",
"note" : "Image from Cupertino (CA).",
"latitudine" : 37.332161,
"longitudine" : -122.030352,
"nomeCartella" : "Foto",
"geoFolderPath" : "\/Users\/cesare\/Desktop",
"radiusCircle" : 50,
"dataCreazione" : "20\/03\/2020",
"nomeArchivio" : "AppleCampus-Image",
"isActive" : true
}
I was unable to implement the solution proposed by #Mdoyle1. I hope someone can edit the code to make it work as it should, without create hidden view.