What I have: View and ViewModel (as extension to View struct).
Both of them are use #EnvironmentObject of type AppState.
The problem is that my preview crashes due to this error:
Fatal error: No ObservableObject of type AppState found.
Commenting out lines in loadUser func saves from crash.
struct ProfileView: View {
#EnvironmentObject var appState: AppState
#ObservedObject var viewModel = ViewModel()
...
}
extension ProfileView {
class ViewModel: ObservableObject {
#EnvironmentObject var appState: AppState
#Published var userVM = UserVM(.example)
init() {
loadUser()
}
func loadUser() {
User.WebService.getSelf { user, errorMsg in
DispatchQueue.main.async {
guard let user = user else {
/*self.appState.showingAlert = true
self.appState.alert = Alert(
title: Text("An error occured!"),
message: Text(errorMsg ?? "unknown error"))*/
return
}
self.userVM = UserVM(user)
}
}
}
}
}
struct ProfileView_Previews: PreviewProvider {
static let viewModel = ProfileView.ViewModel()
static var previews: some View {
let appState = AppState()
appState.activeScreen = .profile
return ProfileView()
.environmentObject(appState)
}
}
Related
I'm trying to capture ProximitySensor activity on SwiftUI.
So I've created a class ProximityOberver and trying to update the attribute 'state' in the notification:
import SwiftUI
import UIKit
class ProximityObserver {
#State var state = false;
#objc func didChange(notification: NSNotification) {
print("MyView::ProximityObserver.didChange")
if let device = notification.object as? UIDevice {
print(device.proximityState)
state = device.proximityState
print(state)
}
}
}
struct ContentView: View {
#State var proximityObserver = ProximityObserver()
func activateProximitySensor() {
print("MyView::activateProximitySensor")
if !UIDevice.current.isProximityMonitoringEnabled {
UIDevice.current.isProximityMonitoringEnabled = true
if UIDevice.current.isProximityMonitoringEnabled {
NotificationCenter.default.addObserver(proximityObserver, selector: #selector(proximityObserver.didChange), name: UIDevice.proximityStateDidChangeNotification, object: UIDevice.current)
}
}
}
func deactivateProximitySensor() {
print("MyView::deactivateProximitySensor")
UIDevice.current.isProximityMonitoringEnabled = false
NotificationCenter.default.removeObserver(proximityObserver, name: UIDevice.proximityStateDidChangeNotification, object: UIDevice.current)
}
var body: some View {
Text(proximityObserver.state ? "true" : "false" )
.animation(.linear(duration: 20).delay(20), value: proximityObserver.state)
.onAppear() {
self.activateProximitySensor()
}
.onDisappear() {
self.deactivateProximitySensor()
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
But even 'state = device.proximityState' code executed, the following print(state) shows the attribute never changed.
MyView::ProximityObserver.didChange
true
false
Can someone explain why this happens, and how to fix this?
Thank you for the comment.
I could fix this as suggested.
class ProximityObserver: ObservableObject {
#Published var state = false;
#objc func didChange(notification: NSNotification) {
print("MyView::ProximityObserver.didChange")
if let device = notification.object as? UIDevice {
print(device.proximityState)
self.state = device.proximityState
print(state, device.proximityState)
}
}
}
struct ContentView: View {
#ObservedObject var proximityObserver = ProximityObserver()
...
I'm trying to figure out the most efficient way to structure this problem..
I'd like to click on the 'EDIT' icon in the dashboard of the MainFragment, display a DialogFragment, allow user to select/deselect up to 5 icons, save the selection, close the DialogFragment, and update the MainFragment.
Should I use MutableLiveData/Observer from a ViewModel? Or is there a better approach? I currently cannot figure out how to use the ViewModel approach correctly...
So far, this is the code I have:
MainFragment: https://i.stack.imgur.com/5fRt2.png
DialogFragment: https://i.stack.imgur.com/ZvW3d.png
ViewModel Class:
class IconDashboardViewModel() : ViewModel(){
var liveDataDashIcons: MutableLiveData<MutableList<String>> = MutableLiveData()
var liveItemData: MutableLiveData<String> = MutableLiveData()
// Observer for live list
fun getLiveDataObserver(): MutableLiveData<MutableList<String>> {
return liveDataDashIcons
}
// Observer for each icon
fun getLiveItemObserver(): MutableLiveData<String> {
return liveItemData
}
// Set icon list
fun setLiveDashIconsList(iconList: MutableLiveData<MutableList<String>>) {
liveDataDashIcons.value = iconList.value
}
// Set data for data
fun setItemData(icon : MutableLiveData<String>) {
liveItemData.value = icon.toString()
}
var iconList = mutableListOf<String>()
}
MainFragment:
private fun populateIconList() : MutableLiveData<MutableList> {
var iconList = viewModel.liveDataDashIcons
// Roster icon
if (roster_dash_layout.visibility == View.VISIBLE) {
iconList.value!!.add(getString(R.string.roster))
} else {
if (iconList.value!!.contains(getString(R.string.roster))) {
iconList.value!!.remove(getString(R.string.roster))
}
}
}
DialogFragment:
private fun setIconList(iconList: MutableList){
var iconList = viewModel.iconList
Log.d(TAG, "viewModel iconList = " + iconList)
if (iconList.contains(getString(R.string.roster))) {
binding.radioButtonRosterPick.setBackgroundResource(R.drawable.icon_helmet_blue_bg)
}
}
I am trying to use PokeApi to make a Pokedex app. I just started swift a couple of days ago so I'm following a tutorial here: https://www.youtube.com/watch?v=UsO-84Xnhww. The tutorial doesn't seem to work, and I don't know how to access the PokeAPI in order to make this app. My code is posted below:
ContentView:
import SwiftUI
struct ContentView: View {
#State var searchText = ""
var pokemon = [Pokemon]()
var body: some View {
NavigationView {
List{
ForEach(searchText == "" ? pokemon : pokemon.filter({
$0.name.contains(searchText.lowercased())
})) { entry in
HStack {
Circle() //Pokemon Image
NavigationLink("\(entry.name)".capitalized, destination: Text("Detail view for \(entry.name)"))
}
}
}
.onAppear {
PokemonManager().getData() { pokemon in self.pokemon = pokemon
for pokemon in pokemon {
print(pokemon.name)
}
}
}
.searchable(text: $searchText)
.navigationTitle("PokePass")
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
PokemonAPI:
import Foundation
struct CurrentPokemon: Codable {
var results: [Pokemon]
}
struct Pokemon: Codable, Identifiable {
var id = UUID()
var name: String
var url: String
}
class PokemonManager {
func getData(completion: #escaping ([Pokemon]) -> ()) {
guard let url = URL(string: "https://pokeapi.co/api/v2/pokemon?limit=151") else {
return
}
URLSession.shared.dataTask(with: url) { (data, _, _) in
guard let data = data else { return }
let pokemonList = try! JSONDecoder().decode(CurrentPokemon.self, from: data)
DispatchQueue.main.async {
completion(pokemonList.results)
}
}
.resume()
}
}
Use let id = UUID() in Pokemon, this will avoid decoding it, and that is what you want, since id is not part of the data.
You can also use this approach:
struct Pokemon: Codable, Identifiable {
var id = UUID()
var name: String
var url: String
enum CodingKeys: String, CodingKey {
case name, url
}
}
EDIT-1
and use #State var pokemon = [Pokemon]() in ContentView
I am trying to observe firebase authentification and update my View accordingly.
I have an SessionStore object:
class SessionStore: ObservableObject {
#Published var session: Account?
var handle: AuthStateDidChangeListenerHandle?
deinit {
stopListen()
}
func listen() {
if handle == nil {
handle = Auth.auth().addStateDidChangeListener { (auth, user) in
if let user = user {
print("User logged in: \(user)")
self.session = Account.preData
} else {
self.session = nil
}
}
}
}
func stopListen() {
if let handle = handle {
Auth.auth().removeStateDidChangeListener(handle)
}
}
}
I use it in a view like this:
struct TabBarView: View {
#EnvironmentObject var sessionStore: SessionStore
#State var selectedTab = Tab.swiping
enum Tab: Int {
case swiping, matches, profil
}
func getUser() {
sessionStore.listen()
}
var body: some View {
Group {
if (sessionStore.session != nil) {
TabView(selection: $selectedTab) {
SwipingView().tabItem {
TabBarItem(text: "Text", image: "pause.circle")
}.tag(Tab.swiping)
}
} else {
LoginView()
}
}.onAppear(perform: getUser).onDisappear(perform: sessionStore.stopListen)
}
}
And call it like this:
sessionStore = SessionStore()
TabBarView().environmentObject(sessionStore!)
But it is only showing the LoginView even when the session is not nil. I made some code changes this is actually the solution.
I think this is the way to do that
class SessionStore: ObservableObject {
#Published var session: Account?
Also you referenced self inside the state closure meaning your object will never deinit. Add unowned or weak like so:
handle = Auth.auth().addStateDidChangeListener { [unowned self] (auth, user) in
https://www.avanderlee.com/swift/weak-self/
The correct implementation is:
class SessionStore: ObservableObject {
let objectWillChange = ObservableObjectPublisher()
var session: Account? {
didSet {
objectWillChange.send()
}
}
var handle: AuthStateDidChangeListenerHandle?
deinit {
stopListen()
}
func listen() {
handle = Auth.auth().addStateDidChangeListener { (auth, user) in
if let user = user {
print("User logged in: \(user)")
self.session = Account.preData
} else {
self.session = nil
}
}
}
func stopListen() {
if let handle = handle {
Auth.auth().removeStateDidChangeListener(handle)
}
}
}
More info about it:
https://www.pointfree.co/blog/posts/30-swiftui-and-state-management-corrections
My application needs to permit additions to the listview. I've figured out how I can dynamically add to a listview by using observableArrayList. If I click on the button, an item gets added to the list and displayed.
Now I'm struggling to add a click handler (I want to handle the event that happens when someone clicks on any item within the list view). Where do I do this?
Here is my code.
package someapp
import javafx.collections.FXCollections
import javafx.geometry.Pos
import javafx.scene.layout.VBox
import javafx.scene.text.FontWeight
import tornadofx.*
class MyApp : App(HelloWorld::class) {
}
class HelloWorld : View() {
val leftSide: LeftSide by inject()
override val root = borderpane {
left = leftSide.root
}
}
class LeftSide: View() {
var requestView: RequestView by singleAssign()
override val root = VBox()
init {
with(root) {
requestView = RequestView()
this += requestView
this += button("Add Item") {
action {
requestView.responses.add( Request( "example.com",
"/foo/bar",
"{ \"foo\" : \"bar\"}".toByteArray()))
}
}
}
}
}
class RequestView : View() {
val responses = FXCollections.observableArrayList<Request>(
)
override val root = listview(responses) {
cellFormat {
graphic = cache {
form {
fieldset {
label(it.hostname) {
alignment = Pos.CENTER_RIGHT
style {
fontSize = 22.px
fontWeight = FontWeight.BOLD
}
}
field("Path") {
label(it.path)
}
}
}
}
}
}
}
class Request(val hostname: String, val path: String, val body: ByteArray) {
}
To configure a callback when an item in a ListView is selected, use the onUserSelect callback:
onUserSelect {
information("You selected $it")
}
You can optionally pass how many clicks constitutes a select as well, default is 2:
onUserSelect(1) {
information("You selected $it")
}
You are using some outdated constructs in your code, here is an updated version converted to best practices :)
class MyApp : App(HelloWorld::class)
class HelloWorld : View() {
override val root = borderpane {
left(LeftSide::class)
}
}
class LeftSide : View() {
val requestView: RequestView by inject()
override val root = vbox {
add(requestView)
button("Add Item").action {
requestView.responses.add(Request("example.com",
"/foo/bar",
"""{ "foo" : "bar"}""".toByteArray()))
}
}
}
class RequestView : View() {
val responses = FXCollections.observableArrayList<Request>()
override val root = listview(responses) {
cellFormat {
graphic = cache {
form {
fieldset {
label(it.hostname) {
alignment = Pos.CENTER_RIGHT
style {
fontSize = 22.px
fontWeight = FontWeight.BOLD
}
}
field("Path") {
label(it.path)
}
}
}
}
}
onUserSelect(1) {
information("You selected $it")
}
}
}
class Request(val hostname: String, val path: String, val body: ByteArray)