I have a piece of code where I'm trying to place Firestore data within a picker. I have made it previously so that the picker will show the Firestore data, but I am unable to select it to show in the 'selected view' therefore I rewrote the code and have the following error "Initializer 'init(_:)' requires that 'getSchoolData' conform to 'StringProtocol' "
Please excuse that it may sound like a daft question I just can't seem to solve it. A copy of my code is below. I have tried working on this for weeks but at a loss so please be kind, I'm new to coding.
Thanks in advance,
import SwiftUI
import Firebase
struct SchoolDetailsView: View {
let schoolData = [getSchoolData()]
#State var selectedSchool = 0
var body: some View {
VStack {
Form {
Section {
Picker(selection: $selectedSchool, label: Text("School Name")) {
ForEach(0 ..< schoolData.count) {
Text(self.schoolData[$0])
}
}
Text("Selected School: \(selectedSchool)")
}
}.navigationBarTitle("Select your school")
}
}
}
struct SchoolPicker_Previews: PreviewProvider {
static var previews: some View {
SchoolDetailsView()
}
}
class getSchoolData : ObservableObject{
#Published var datas = [schoolName]()
init() {
let db = Firestore.firestore()
db.collection("School Name").addSnapshotListener { (snap, err) in
if err != nil{
print((err?.localizedDescription)!)
return
}
for i in snap!.documentChanges{
let id = i.document.documentID
let name = i.document.get("Name") as! String
self.datas.append(schoolName(id: id, name: name))
}
}
}
}
struct schoolName : Identifiable {
var id : String
var name : String
}
You may try the following:
struct SchoolDetailsView: View {
#ObservedObject var schoolData = getSchoolData() // make `#ObservedObject`/`#StateObject` instead of const array
#State var selectedSchool = "" // `schoolName.id` is of type String
var body: some View {
VStack {
Form {
Section {
Picker(selection: $selectedSchool, label: Text("School Name")) {
ForEach(schoolData.datas, id: \.id) { // choose whether you want to tag by `id` or by `name`
Text($0.name)
}
}
Text("Selected School: \(selectedSchool)")
}
}.navigationBarTitle("Select your school")
}
}
}
Related
I am trying to open a sheet when tapping on an item. I followed this questions Sheet inside ForEach doesn't loop over items SwiftUI answer. I get this Error: The compiler is unable to type-check this expression in reasonable time; try breaking up the expression into distinct sub-expressions, I don't understand what is causing it. I tried multiple solutions and they all lead to the same Error.
#State var selectedSong: Int? = nil
#State var songList: [AlbumSong] = []
VStack {
ForEach(songList.enumerated().reversed(), id: \.offset) { index, song in
HStack {
Text("\(index + 1).").padding(.leading, 8)
VStack {
Text(song.title)
Text(song.artist)
}
}.onTapGesture {
self.selectedSong = index
}
}
}
}
.sheet(item: self.$selectedSong) { selectedMovie in
SongPickerEdit(songList: $songList, songIndex: selectedMovie)
I also tried setting songIndex to being an AlbumSong and then implemented this sheet:
.sheet(item: self.$selectedSong) {
SongPickerEdit(songList: $songList, songIndex: self.songList[$0])
}
struct SongPickerEdit: View {
#Binding var songList: [AlbumSong]
#State var songIndex: Int?
var body: some View {
}
}
struct AlbumSong: Identifiable, Codable {
#DocumentID var id: String?
let title: String
let duration: TimeInterval
var image: String
let artist: String
let track: String
}
How about making selectedSong an AlbumSong?? The item: parameter needs to be an Identifiable binding, but Int is not Identifiable.
#State var selectedSong: AlbumSong? = nil
#State var songList: [AlbumSong] = []
var body: some View {
List {
ForEach(songList.enumerated().reversed(), id: \.offset) { index, song in
HStack {
Text("\(index + 1).").padding(.leading, 8)
VStack {
Text(song.title)
Text(song.artist)
}
}.onTapGesture {
self.selectedSong = song
}
}
}.sheet(item: $selectedSong) { song in
SongPickerEdit(songList: $songList, song: song)
}
}
Note that SongPickerEdit would look like this:
struct SongPickerEdit: View {
#State var song: AlbumSong
var body: some View {
Text("\(song.title), \(song.artist)")
}
}
If you really need the index for some reason, you can add the song list binding back in and use songList.index { $0.id == song.id } to find the index if the list is not too long.
Otherwise, you can make your own Identifiable type SongAndIndex that uses the same id as AlbumSong, but with an extra index property, and use that as the type of selectedSong.
A third way would be to use the sheet(isPresented:) overload, but this way you end up with 2 sources of truth:
#State var selectedSongIndex: Int? = nil {
didSet {
if selectedSongIndex != nil {
isSheetPresented = true
}
}
}
#State var isSheetPresented: Bool = false {
didSet {
if !isSheetPresented {
selectedSongIndex = nil
}
}
}
...
}.sheet(isPresented: $isSheetPresented) {
SongPickerEdit(songList: $songList, songIndex: selectedSongIndex)
}
selectedSongIndex also won't be set to nil when the user dismisses the sheet.
I have a simple SwiftUI view with a Picker containing a list of objects from a data array. The Picker lists the objects just fine, but the selected value is not being saved to the binding variable $selectedCar. It returns empty string. This is the view in question:
struct GarageSpace: View {
var currentUserID: String
#Environment(\.presentationMode) var presentationMode
#Binding var selectedPlaceID: String
#Binding var selectedPlaceName: String
#Binding var selectedPlaceDate: Date
#Binding var selectedSpaceID: String
#State var selectedCar: String
#Binding var cars: CarArrayObject
var body: some View {
VStack{
Group{
Picker("Car", selection: $selectedCar) {
if let cars = cars{
ForEach(cars.dataArray, id: \.self) {car in
let year = car.year! as String
let make = car.make as String
let model = car.model! as String
let string = year + " " + make + " " + model
Text(string) //displays correctly in Picker
}
}
}
Spacer()
if let cars = cars {
Button {
print("yes")
print(selectedCar) //returns empty string
} label: {
Text("Confirm")
}
}
}
}
}
}
The above view is displayed via a NavigationLink on the previous screen:
NavigationLink(destination: GarageSpace(currentUserID: currentUserID, selectedPlaceID: $selectedPlaceID, selectedPlaceName: $selectedPlaceName, selectedPlaceDate: $selectedPlaceDate, selectedSpaceID: $selectedSpaceID, selectedCar: "", cars: $cars)) {
}
This NavigationLink might be the culprit because I'm sending an empty string for selectedCar. However, it forces me to initialize a value with the NavigationLink.
Any ideas? Thanks!
EDIT:
Added a tag of type String, still same outcome:
Text(string).tag(car.carID)
EDIT: FOUND THE ISSUE! However, I'm still stumped. The selection variable is empty because I wasn't pressing on the Picker since I only had one item in the array. How can I get the Picker to "select" an item if it's the only one in the array by default?
With tag, all works well in my simple tests. Here is my test code:
import SwiftUI
#main
struct TestApp: App {
var body: some Scene {
WindowGroup {
ContentView()
}
}
}
struct ContentView: View {
var body: some View {
GarageSpace()
}
}
struct GarageSpace: View {
#State var selectedCar: String = ""
#State var cars: CarArrayObject? = CarArrayObject(car: CarModel(make: "Ford"))
var body: some View {
VStack {
Group {
Picker("Car", selection: $selectedCar) {
if let cars = cars {
ForEach(cars.dataArray, id: \.self) { car in
Text(car.make).tag(car.carID)
}
}
}
Spacer()
if let cars = cars {
Button {
print("----> selectedCar carID: \(selectedCar)")
} label: {
Text("Show selected carID")
}
}
}
}
// optional, to select the first car
.onAppear {
if let cars = cars {
selectedCar = (cars.dataArray.first != nil) ? cars.dataArray.first!.carID : ""
}
}
}
}
struct CarModel: Hashable {
var make = ""
var carID = UUID().uuidString
}
class CarArrayObject: ObservableObject{
// for testing
#Published var dataArray = [CarModel(make: "Toyota"), CarModel(make: "Suzuki"), CarModel(make: "VW")]
/// USED FOR SINGLE CAR SELECTION
init(car: CarModel) {
self.dataArray.append(car)
}
/// USED FOR GETTING CARS FOR USER PROFILE
init(userID: String) {
// print("GET CARS FOR USER ID \(userID)")
// DataService.instance.downloadCarForUser(userID: userID) { (returnedCars) in
//
// let sortedCars = returnedCars.sorted { (car1, car2) -> Bool in
// return car1.dateCreated > car2.dateCreated
// }
// self.dataArray.append(contentsOf: sortedCars)
// }
}
}
This question already has answers here:
How to change a value of struct that is in array?
(2 answers)
Closed 1 year ago.
I'm trying to achieve a two way binding-like functionality.
I have a model with an array of identifiable Items, var selectedID holding a UUID of selected Item, and var proxy which has get{} that looks for an Item inside array by UUID and returns it.
While get{} works well, I can't figure out how to make proxy mutable to change values of selected Item by referring to proxy.
I have tried to implement set{} but nothing works.
import SwiftUI
var words = ["Aaaa", "Bbbb", "Cccc"]
struct Item: Identifiable {
var id = UUID()
var word: String
}
class Model: ObservableObject {
#Published var items: [Item] = [Item(word: "One"), Item(word: "Two"), Item(word: "Three")]
#Published var selectedID: UUID?
var proxy: Item? {
set {
// how to set one property of Item?, but not the whole Item here?
}
get {
let index = items.firstIndex(where: { $0.id == selectedID })
return index != nil ? items[index!] : nil
}
}
}
struct ContentView: View {
#StateObject var model = Model()
var body: some View {
VStack {
// monitoring
MonitorkVue(model: model)
//selections
HStack {
ForEach(model.items.indices, id:\.hashValue) { i in
SelectionVue(item: $model.items[i], model: model)
}
}
}.padding()
}
}
struct MonitorkVue: View {
#ObservedObject var model: Model
var body: some View {
VStack {
Text(model.proxy?.word ?? "no proxy")
// 3rd: cant make item change by referring to proxy
// in order this to work, proxy's set{} need to be implemented somehow..
Button {
model.proxy?.word = words.randomElement()!
} label: {Text("change Proxy")}
}
}
}
struct SelectionVue: View {
#Binding var item: Item
#ObservedObject var model: Model
var body: some View {
VStack {
Text(item.word).padding()
// 1st: making selection
Button {
model.selectedID = item.id } label: {Text("SET")
}.disabled(item.id != model.selectedID ? false : true)
// 2nd: changing item affects proxy,
// this part works ok
Button {
item.word = words.randomElement()!
}label: {Text("change Item")}
}
}
}
Once you SET selection you can randomize Item and proxy will return new values.
But how to make it works the other way around when changing module.proxy.word = "Hello" would affect selected Item?
Does anyone knows how to make this two-way shortct?
Thank You
Here is a correction and some fix:
struct Item: Identifiable {
var id = UUID()
var word: String
}
class Model: ObservableObject {
#Published var items: [Item] = [Item(word: "One"), Item(word: "Two"), Item(word: "Three")]
#Published var selectedID: UUID?
var proxy: Item? {
get {
if let unwrappedIndex: Int = items.firstIndex(where: { value in (selectedID == value.id) }) { return items[unwrappedIndex] }
else { return nil }
}
set(newValue) {
if let unwrappedItem: Item = newValue {
if let unwrappedIndex: Int = items.firstIndex(where: { value in (unwrappedItem.id == value.id) }) {
items[unwrappedIndex] = unwrappedItem
}
}
}
}
}
I am trying to make a list of eatery locations each of which are displayed in an EateryRow which is able to be clicked to move to the EateryDetail page, however with the implementation of this code I get an error which I believe is related to the syntax of the NavigationLink argument.
Also: I found this question which seems to have the same problem as me but it remains unanswered.
import SwiftUI
struct EateryList: View {
#Binding var eateries: [Eatery]
var body: some View {
NavigationView {
VStack {
List {
ForEach(eateries) {
NavigationLink(destination: EateryDetail(eatery: $eateries[identifiedBy: $0])) { //error here
EateryRow(eatery: $eateries[identifiedBy: $0])
}
}
.onMove {
eateries.move(fromOffsets: $0, toOffset: $1)
EateriesApp.save()
}.onDelete {
eateries.remove(atOffsets: $0)
EateriesApp.save()
}
}
.navigationTitle("Favourite Eateries")
.navigationBarItems(leading: EditButton(), trailing: Button( action: add)
{
Image(systemName: "plus")
}
)
.listStyle(InsetGroupedListStyle())
}
}
}
func add() {
eateries.append(Eatery(name: "Eatery", location: "Insert location here", notes: "Insert notes here", reviews: ["Insert reviews here"], url: "https://i.imgur.com/y3MMnba.png"))
EateriesApp.save()
}
}
I get this error on the line with the NavigationLink:
Unnamed argument #2 must precede argument 'destination'
For further clarity this is how I've used the "eatery" variable in the EateryDetail and EatertyRow views:
struct EateryDetail: View {
#Binding var eatery: Eatery
struct EateryRow: View {
#Binding var eatery: Eatery
And here is my code for Eatery which is defined in a file called eateries.swift:
import Foundation
struct Eatery: Codable, Identifiable {
var id = UUID()
var name: String
var location: String
var notes: String
var reviews: [String] = []
var url: String = ""
}
In eateriesApp.swift this is also defined:
import SwiftUI
#main
struct EateriesApp: App {
#State var model: [Eatery] = EateriesApp.model
static var model: [Eatery] = {
guard let data = try? Data(contentsOf: EateriesApp.fileURL),
let model = try? JSONDecoder().decode([Eatery].self, from: data) else {
return [elCaminoCantina, theFineDine, nightBites, theRiverRodeo, theCozyKitchen, theElegantEatery]
}
return model
}()
static var modelBinding: Binding<[Eatery]>?
var body: some Scene {
EateriesApp.modelBinding = $model
return WindowGroup {
ContentView(eateries: $model)
}
}
You should need to use .indices in ForEach(eateries).
Like this
ForEach(eateries.indices) { index in
NavigationLink(destination: EateryDetail(eatery: $eateries[index])) { //error here
EateryRow(eatery: $eateries[index])
}
}
The problem is you are using a shorthand variable ($0). When you used $0 inside the NavigationLink then $0 is considered for NavigationLink not ForEach. so now both $0 are in conflict in your case.
You can check with the below code. In below code now not produce any error because now there is no use $0 inside the NavigationLink
ForEach(eateries) {
Text($0.name)
NavigationLink(destination: EateryDetail(eatery: $eateries[identifiedBy: $0])) {
Text("$0.name")
}
}
Another solution is to use one variable and store your $0 data like this.
ForEach(eateries) {
let eaterie = $0 //<--- Here
NavigationLink(destination: EateryDetail(eatery: $eateries[identifiedBy: eaterie])) { //<--- Here
EateryRow(eatery: $eateries[identifiedBy: eaterie]) //<--- Here
}
}
I was very kindly helped to allow my picker to select a value from my Firestore database. What I would like to do is once that value is selected in my picker I would like to be able to show that value in other views. I have tried setting this up using UserDefaults but I'm not sure that's the way to go? If you could suggest a better method I'd be more than grateful. My code currently is below.
The value in the below code returns Unknown School each time but without the user defaults works flawlessly in fetching the data.
Thanks in advance.
import SwiftUI
import Firebase
struct SchoolDetailsView: View {
#ObservedObject var schoolData = getSchoolData()
#State private var selectedSchool = UserDefaults.standard.string(forKey: "") // `schoolName.id` is of type String
var body: some View {
VStack {
Form {
Section {
Picker(selection: $selectedSchool, label: Text("School Name")) {
ForEach(schoolData.datas, id: \.id) {
Text($0.name)
}
}
Text("Selected School: \(selectedSchool ?? "Unknown School")")
}
}.navigationBarTitle("School Selection")
}
}
struct SchoolPicker_Previews: PreviewProvider {
static var previews: some View {
SchoolDetailsView()
}
}
class getSchoolData : ObservableObject{
#Published var datas = [schoolName]()
init() {
let db = Firestore.firestore()
db.collection("School Name").addSnapshotListener { (snap, err) in
if err != nil{
print((err?.localizedDescription)!)
return
}
for i in snap!.documentChanges{
let id = i.document.documentID
let name = i.document.get("Name") as! String
self.datas.append(schoolName(id: id, name: name))
}
}
}
}
struct schoolName : Identifiable {
var id : String
var name : String
}
}
First, the UserDefaults key for your variable can't be empty:
#State private var selectedSchool: String = UserDefaults.standard.string(forKey: "selectedSchool") ?? "Unknown School"
Then you can use onReceive to update the variable:
.onReceive(Just(selectedSchool)) {
UserDefaults.standard.set($0, forKey: "selectedSchool")
}
Full code:
import Combine
import Firebase
import SwiftUI
struct SchoolDetailsView: View {
#ObservedObject var schoolData = getSchoolData()
#State private var selectedSchool = UserDefaults.standard.string(forKey: "selectedSchool")
var body: some View {
VStack {
Form {
Section {
Picker(selection: $selectedSchool, label: Text("School Name")) {
ForEach(schoolData.datas, id: \.id) {
Text($0.name)
}
}
.onReceive(Just(selectedSchool)) {
UserDefaults.standard.set($0, forKey: "selectedSchool")
}
Text("Selected School: \(selectedSchool)")
}
}.navigationBarTitle("School Selection")
}
}
}
Note that in SwiftUI 2 / iOS 14 you can use #AppStorage instead.