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...
