How can the destination of a NavigationLink can modified to detect which item within a list was clicked? An if statement of some sort would be very helpful but all items currently do the same thing.
import SwiftUI
let textTitle = NSLocalizedString("PageTitle", comment: "")
let textItemA = NSLocalizedString("ItemA", comment: "")
let textItemB = NSLocalizedString("ItemB", comment: "")
let textItemC = NSLocalizedString("ItemC", comment: "")
struct ItemMain: Identifiable {
var id = UUID()
var name: String
}
let myItems: [MyItem] = [
MyItem(name: textItemA),
MyItem(name: textItemB),
MyItem(name: textItemC)]
struct ContentView: View {
#State private var showingAlert = false
var body: some View {
NavigationView{
List(myItems) { myItem in
NavigationLink(destination: MyDetailView(myItem: myItem)) {
Text(myItem.name)
}
}
.navigationBarTitle(textTitle)
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
struct MyDetailView: View {
var myItem: MyItem
var body: some View {
Text(myIem.name)
}
}
I customized your MyItem model as it is not provided by you
enum MyItemType {
case navigation
case alert
}
struct MyItem: Identifiable {
let id = UUID()
let name: String
var type: MyItemType = .alert
}
And made changed to your ContentView
struct ContentView: View {
#State private var showingAlert = false
var body: some View {
NavigationView{
listView
.navigationBarTitle(textTitle)
}
.alert(isPresented: $showingAlert) {
//Customise your alert according to your need
Alert(title: Text("Alert"))
}
}
private var listView: some View {
List(myItems) { myItem in
if myItem.type == .navigation {
NavigationLink(destination: MyDetailView(myItem: myItem)) {
Text(myItem.name)
}
} else {
Button(action: {
self.showingAlert = true
}) {
Text(myItem.name)
}
}
}
}
}
And lastly your myItems array:
let myItems: [MyItem] = [
MyItem(name: textItemA, type: MyItemType.navigation),
MyItem(name: textItemB),
MyItem(name: textItemC)
]
You can use if statement inside the ForEach to specify special cases:
List(myItems) { myItem in
if (myItem.name == "ItemA") //<<< Here goes your if
{
NavigationLink(destination: MyDetailView(myItem: myItem)) {
Text(myItem.name)
}
}
else
{
//show your alert here
Related
I am curious why this .fullScreenCover display of a view does not update properly with a passed-in parameter unless the parameter is using the #Binding property wrapper. Is this a bug or intended behavior? Is this the fact that the view shown by the fullScreenCover is not lazily generated?
import SwiftUI
struct ContentView: View {
#State private var showFullScreen = false
#State private var message = "Initial Message"
var body: some View {
VStack {
Button {
self.message = "new message"
showFullScreen = true
} label: {
Text("Show Full Screen")
}
}.fullScreenCover(isPresented: $showFullScreen) {
TestView(text: message)
}
}
}
struct TestView: View {
var text: String
var body: some View {
Text(text)
}
}
There is a different fullScreenCover for passing in dynamic data, e.g.
import SwiftUI
struct CoverData: Identifiable {
var id: String {
return message
}
let message: String
}
struct FullScreenCoverTestView: View {
#State private var coverData: CoverData?
var body: some View {
VStack {
Button {
coverData = CoverData(message: "new message")
} label: {
Text("Show Full Screen")
}
}
.fullScreenCover(item: $coverData, onDismiss: didDismiss) { item in
TestView(text: item.message)
.onTapGesture {
coverData = nil
}
}
}
func didDismiss() {
// Handle the dismissing action.
}
}
struct TestView: View {
let text: String
var body: some View {
Text(text)
}
}
More info and an example in the docs:
https://developer.apple.com/documentation/SwiftUI/AnyView/fullScreenCover(item:onDismiss:content:)
I am attempting to set up a SwiftUI weather app. when the user searches for a city name in the textfield then taps the search button, a NavigationLink list item should appear in the list. Then, the user should be able to click the navigation link and re-direct to a detail view. My goal is to have the searched navigation links to populate a list. However, my search cities are not populating in the list, and I'm not sure why. In ContentView, I setup a list with a ForEach function that passes in cityNameList, which is an instance of the WeatherViewModel. My expectation is that Text(city.title) should display as a NavigationLink list item. How should I configure the ContentView or ViewModel to populate the the list with NavigationLink list items? See My code below:
ContentView
import SwiftUI
struct ContentView: View {
// Whenever something in the viewmodel changes, the content view will know to update the UI related elements
#StateObject var viewModel = WeatherViewModel()
#State private var cityName = ""
var body: some View {
NavigationView {
VStack {
TextField("Enter City Name", text: $cityName).textFieldStyle(.roundedBorder)
Button(action: {
viewModel.fetchWeather(for: cityName)
cityName = ""
}, label: {
Text("Search")
.padding(10)
.background(Color.green)
.foregroundColor(Color.white)
.cornerRadius(10)
})
List {
ForEach(viewModel.cityWeather, id: \.id) { city in
NavigationLink(destination: DetailView(detail: viewModel)) {
HStack {
Text(city.cityWeather.name)
.font(.system(size: 32))
}
}
}
}
Spacer()
}
.navigationTitle("Weather MVVM")
}.padding()
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
ViewModel
import Foundation
class WeatherViewModel: ObservableObject {
//everytime these properties are updated, any view holding onto an instance of this viewModel will go ahead and updated the respective UI
#Published var cityWeather: WeatherModel = WeatherModel()
func fetchWeather(for cityName: String) {
guard let url = URL(string: "https://api.openweathermap.org/data/2.5/weather?q=\(cityName)&units=imperial&appid=<MyAPIKey>") else {
return
}
let task = URLSession.shared.dataTask(with: url) { data, _, error in
// get data
guard let data = data, error == nil else {
return
}
//convert data to model
do {
let model = try JSONDecoder().decode(WeatherModel.self, from: data)
DispatchQueue.main.async {
self.cityWeather = model
}
}
catch {
print(error)
}
}
task.resume()
}
}
Model
import Foundation
struct WeatherModel: Identifiable, Codable {
var id = UUID()
var name: String = ""
var main: CurrentWeather = CurrentWeather()
var weather: [WeatherInfo] = []
func firstWeatherInfo() -> String {
return weather.count > 0 ? weather[0].description : ""
}
}
struct CurrentWeather: Codable {
var temp: Float = 0.0
}
struct WeatherInfo: Codable {
var description: String = ""
}
DetailView
import SwiftUI
struct DetailView: View {
var detail: WeatherViewModel
var body: some View {
VStack(spacing: 20) {
Text(detail.cityWeather.name)
.font(.system(size: 32))
Text("\(detail.cityWeather.main.temp)")
.font(.system(size: 44))
Text(detail.cityWeather.firstWeatherInfo())
.font(.system(size: 24))
}
}
}
struct DetailView_Previews: PreviewProvider {
static var previews: some View {
DetailView(detail: WeatherViewModel.init())
}
}
try something like this example code, works well for me:
struct WeatherModel: Identifiable, Codable {
let id = UUID()
var name: String = ""
var main: CurrentWeather = CurrentWeather()
var weather: [WeatherInfo] = []
func firstWeatherInfo() -> String {
return weather.count > 0 ? weather[0].description : ""
}
}
struct CurrentWeather: Codable {
var temp: Float = 0.0
}
struct WeatherInfo: Codable {
var description: String = ""
}
struct ContentView: View {
// Whenever something in the viewmodel changes, the content view will know to update the UI related elements
#StateObject var viewModel = WeatherViewModel()
#State private var cityName = ""
var body: some View {
NavigationView {
VStack {
TextField("Enter City Name", text: $cityName).textFieldStyle(.roundedBorder)
Button(action: {
viewModel.fetchWeather(for: cityName)
cityName = ""
}, label: {
Text("Search")
.padding(10)
.background(Color.green)
.foregroundColor(Color.white)
.cornerRadius(10)
})
List {
ForEach(viewModel.cityNameList) { city in
NavigationLink(destination: DetailView(detail: city)) {
HStack {
Text(city.name).font(.system(size: 32))
}
}
}
}
Spacer()
}.navigationTitle("Weather MVVM")
}.navigationViewStyle(.stack)
}
}
struct DetailView: View {
var detail: WeatherModel
var body: some View {
VStack(spacing: 20) {
Text(detail.name).font(.system(size: 32))
Text("\(detail.main.temp)").font(.system(size: 44))
Text(detail.firstWeatherInfo()).font(.system(size: 24))
}
}
}
class WeatherViewModel: ObservableObject {
#Published var cityNameList = [WeatherModel]()
func fetchWeather(for cityName: String) {
guard let url = URL(string: "https://api.openweathermap.org/data/2.5/weather?q=\(cityName)&units=imperial&appid=YOURKEY") else { return }
let task = URLSession.shared.dataTask(with: url) { data, _, error in
guard let data = data, error == nil else { return }
do {
let model = try JSONDecoder().decode(WeatherModel.self, from: data)
DispatchQueue.main.async {
self.cityNameList.append(model)
}
}
catch {
print(error) // <-- you HAVE TO deal with errors here
}
}
task.resume()
}
}
I'd like the ability to edit and put into a new view the 'expenses' the user adds. I've been having problems accessing the data after a new expense has been added. I am able to delete the items and add them up but I'd like to click on the 'expenses' and see and edit the content in them Image of the view
//Content View
import SwiftUI
struct ExpenseItem: Identifiable, Codable {
let id = UUID()
let name: String
let type: String
let amount: Int
}
class Expenses: ObservableObject {
#Published var items = [ExpenseItem]() {
didSet {
let encoder = JSONEncoder()
if let encoded = try?
encoder.encode(items) {
UserDefaults.standard.set(encoded, forKey: "Items")
}
}
}
init() {
if let items = UserDefaults.standard.data(forKey: "Items") {
let decoder = JSONDecoder()
if let decoded = try?
decoder.decode([ExpenseItem].self, from: items) {
self.items = decoded
return
}
}
}
// Computed property that calculates the total amount
var total: Int {
self.items.reduce(0) { result, item -> Int in
result + item.amount
}
}
}
struct ContentView: View {
#ObservedObject var expenses = Expenses()
#State private var showingAddExpense = false
var body: some View {
NavigationView {
List {
ForEach(expenses.items) { item in
HStack {
VStack {
Text(item.name)
.font(.headline)
Text(item.type)
}
Spacer()
Text("$\(item.amount)")
}
}
.onDelete(perform: removeItems)
// View that shows the total amount of the expenses
HStack {
Text("Total")
Spacer()
Text("\(expenses.total)")
}
}
.navigationBarTitle("iExpense")
.navigationBarItems(trailing: Button(action: {
self.showingAddExpense = true
}) {
Image(systemName: "plus")
}
)
.sheet(isPresented: $showingAddExpense) {
AddView(expenses: self.expenses)
}
}
}
func removeItems(at offsets: IndexSet) {
expenses.items.remove(atOffsets: offsets)
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
//AddExpense
import SwiftUI
struct AddView: View {
#Environment(\.presentationMode) var presentationMode
#ObservedObject var expenses: Expenses
#State private var name = ""
#State private var type = "Personal"
#State private var amount = ""
static let types = ["Business", "Personal"]
var body: some View {
NavigationView {
Form {
TextField("Name", text: $name)
Picker("Type", selection: $type) {
ForEach(Self.types, id: \.self) {
Text($0)
}
}
TextField("Amount", text: $amount)
.keyboardType(.numberPad)
}
.navigationBarTitle("Add new expense")
.navigationBarItems(trailing: Button("Save") {
if let actualAmount = Int(self.amount) {
let item = ExpenseItem(name: self.name, type: self.type, amount: actualAmount)
self.expenses.items.append(item)
self.presentationMode
.wrappedValue.dismiss()
}
})
}
}
}
struct AddView_Previews: PreviewProvider {
static var previews: some View {
AddView(expenses: Expenses())
}
}
Remove #observedObject in AddView.
A view cannot change an ObservableObject. ObservableObject is used for being notified when a value is changed.
When you pass the expenses class to AddView, you are giving it a reference. Therefore, AddView can change the expenses, and consequently update ContentView.
So I have a list that changes when user fill in search keyword, and when there is no result, all the cells collapse and somehow they would fly over to the first section which looks ugly. Is there an error in my code or is this an expected SwiftUI behavior? Thanks.
import SwiftUI
struct ContentView: View {
#ObservedObject var viewModel = ViewModel(photoLibraryService: PhotoLibraryService.shared)
var body: some View {
NavigationView {
List {
Section {
TextField("Enter Album Name", text: $viewModel.searchText)
}
Section {
if viewModel.libraryAlbums.count > 0 {
ForEach(viewModel.libraryAlbums) { libraryAlbum -> Text in
let title = libraryAlbum.assetCollection.localizedTitle ?? "Album"
return Text(title)
}
}
}
}.listStyle(GroupedListStyle())
.navigationBarTitle(
Text("Albums")
).navigationBarItems(trailing: Button("Add Album", action: {
PhotoLibraryService.shared.createAlbum(withTitle: "New Album \(Int.random(in: 1...100))")
}))
}.animation(.default)
}
}
1) you have to use some debouncing to reduce the needs to refresh the list, while typing in the search field
2) disable animation of rows
The second is the hardest part. the trick is to force recreate some View by setting its id.
Here is code of simple app (to be able to test this ideas)
import SwiftUI
import Combine
class Model: ObservableObject {
#Published var text: String = ""
#Published var debouncedText: String = ""
#Published var data = ["art", "audience", "association", "attitude", "ambition", "assistance", "awareness", "apartment", "artisan", "airport", "atmosphere", "actor", "army", "attention", "agreement", "application", "agency", "article", "affair", "apple", "argument", "analysis", "appearance", "assumption", "arrival", "assistant", "addition", "accident", "appointment", "advice", "ability", "alcohol", "anxiety", "ad", "activity"].map(DataRow.init)
var filtered: [DataRow] {
data.filter { (row) -> Bool in
row.txt.lowercased().hasPrefix(debouncedText.lowercased())
}
}
var id: UUID {
UUID()
}
private var store = Set<AnyCancellable>()
init(delay: Double) {
$text
.debounce(for: .seconds(delay), scheduler: RunLoop.main)
.sink { [weak self] (s) in
self?.debouncedText = s
}.store(in: &store)
}
}
struct DataRow: Identifiable {
let id = UUID()
let txt: String
init(_ txt: String) {
self.txt = txt
}
}
struct ContentView: View {
#ObservedObject var search = Model(delay: 0.5)
var body: some View {
NavigationView {
VStack(alignment: .leading) {
TextField("filter", text: $search.text)
.padding(.vertical)
.padding(.horizontal)
List(search.filtered) { (e) in
Text(e.txt)
}.id(search.id)
}.navigationBarTitle("Navigation")
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
and i am happy with the result
I have ViewModel which looks like this:
class ItemsListViewModel : ObservableObject{
var response : ItemsListResponse? = nil
var itemsList : [ListItem] = []
var isLoading = true
let objectWillChange = PassthroughSubject<Void, Never>()
func getItems() {
self.isLoading = true
ApiManager.shared.getItems()
.sink(receiveCompletion: {completion in
}, receiveValue: {
self.response = data
self.isLoading = false
self.objectWillChange.send()
})
}
}
When I receive data from network request I use self.objectWillChange.send() to notify view, but view do not react to this.
My views :
ItemsView
struct ItemsView: View {
var body: some View {
VStack{
Text("Some Title")
ItemsListView()
}
}
}
ItemsListView
struct ItemsListView: View {
#ObservedObject var myViewModel = ItemsListViewModel()
var body: some View {
VStack{
Text("\(self.myViewModel.response?.total")
}.onAppear{
self.myViewModel.getItems()
}
}
}
But the interesting thing, that if I use ItemsListView not inside
ItemsView everything works perfectly. How can i solve this problem?
try this ( i simplified just your model to test in playground)
you can copy directly the code in playground and check
struct Model {
var items : [String]
}
class ItemsListViewModel : ObservableObject {
#Published var items : [String] = ["Test 1", "Test2"]
}
let myViewModel = ItemsListViewModel()
struct ItemsView: View {
var body: some View {
VStack{
Text("Some Title")
ItemsListView().environmentObject(myViewModel)
}
}
}
struct ItemsListView: View {
#EnvironmentObject private var model : ItemsListViewModel
var body: some View {
VStack{
Text("\(model.items.count)")
}
}
}
struct ContentView: View {
var body: some View {
ItemsView()
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView().environmentObject(myViewModel)
}
}
Using #Published for properties of ObservableObject does fix your issue. See simplified below demo:
import SwiftUI
import Combine
class ItemsListViewModel : ObservableObject{
#Published var response = ""
var isLoading = true
func getData() {
self.isLoading = true
DispatchQueue.main.async {
Just("test")
.sink(receiveCompletion: {completion in
}, receiveValue: { data in
self.response = data
self.isLoading = false
})
}
}
}
struct ItemsListView: View {
#ObservedObject var myViewModel = ItemsListViewModel()
var body: some View {
VStack{
Text("\(self.myViewModel.response)")
}.onAppear{
self.myViewModel.getData()
}
}
}
struct ItemsView: View {
var body: some View {
VStack{
Text("Some Title")
ItemsListView()
}
}
}
struct TestPublished: View {
var body: some View {
ItemsView()
}
}
struct TestPublished_Previews: PreviewProvider {
static var previews: some View {
TestPublished()
}
}