I am trying to pass data to a new view in my app, so that my script can plug the data into the link and fetch the respective article information. My view is being called with ArticleView(articleID: 0) though this changes with the ID of the article. The beginning of my view begins as such...
struct ArticleView: View {
var articleID: Int
#Envionment(.\imageCache) var cache: ImageCache
#ObservedObject private var data = Result2()
let defaults = UserDefaults.standard
...
init() {
self.data.results.append(Story.init(id: 0, title: "test", image: "", story: "", published: "", author: ""))
self.loadArticle(CDNLink: "http://\(self.defaults.object(forKey: "domain") as! String)/cdn?funct=fetchArticle&articleID=\(self.articleID)")
}
What I am trying to understand is how do I get the article id from my dashboard to being stored in var articleID so my loadArticle function can then run the script and pull the content in? I can provide the information for Result2() along with the data structures for Response2 and Story upon request. Thanks!
You have 2 options:
To ask for a parameter from initializer:
struct ArticleView: View {
var articleID: Int
...
init(articleID: Int) {
self.articleID = articleID
// Do whatever you need
}
var body: some View {
SomeView()
}
}
Omit initializer and put all you need in .onAppear clause
struct ArticleView: View {
var articleID: Int
...
var body: some View {
SomeView()
.onApppear {
// Do whatever you need
}
}
}
In second case the compiler will create an initializer automatically with all values needed (in your case - articleID)
Related
In essence, I'm learning by creating a simple app that takes an ISBN and returns the book information. I've created a view file to display this information along with a text entry for capturing the ISBN. The logic side of things as pertaining to getting the information from the internet is fine, however, when I try to update the view with the modified variables, it only prints them as declared, and NOT redrawing them after modification. Any advice would be appreciated. Thanks!
This specific example references #Published var test = "Testing 1 2 3 as the default, and after the search, the var is modified to test = modified text which is then printed in the text view of TestView.swift. The print statement correctly displays the modified text, however it does not update in the view in which it is passed. The goal is to pass the final dictionary, but for testing purposes I'm using a simple string variable.
TestFile.swift
import Foundation
import SwiftyXMLParser
import SwiftUI
class getdata: ObservableObject {
#Published var outputDict: [String:String] = [:]
#Published var test = "Testing 1 2 3"
.
.
//code to grab xml from url
.
.
func parseData(input: String) {
var title: String?
var author: String?
let xml = try! XML.parse(input)
if let text = xml["GoodreadsResponse", "book", "title"].text {
title = text
outputDict["title"] = title
}
if let text = xml["GoodreadsResponse", "book", "authors", "author", "name"].text {
author = text
outputDict["author"] = author
}
print("Title: \(outputDict["title"]!), Author: \(outputDict["author"]!)")
test = "modified text"
print(test)
}
}
TestView.swift
import SwiftUI
struct testView: View {
#State var textEntry: String = ""
#ObservedObject var viewModel: getdata
var body: some View {
let try1 = getdata()
VStack {
TextField("Enter ISBN", text: $textEntry)
.padding()
Button(action: {try1.getData(bookID: textEntry)}, label: {
Text("Search")
})
Text("Title: \(self.viewModel.test)")
}
}
}
struct testView_Previews: PreviewProvider {
static var previews: some View {
testView(viewModel: getdata())
}
}
Although I don't think your example compiles, and you haven't provided the definitions of some of the functions, I can point you at one error:
Inside the body of the view you are creating a new Observable object:
let try1 = getdata()
And your Button calls messages on this:
Button(action: {try1.getData(bookID: textEntry)}...
But your TextView reads from the original viewModel:
Text("Title: \(self.viewModel.test)")
You are interacting with try1, but deriving your view from viewModel. They are separate objects.
I'm new to Swift so I hope this isn't something really silly. I'm trying to build an array of Structs, and one of the parameters is another Array with another Struct in it. I'm not sure if there is a better way, but I thought I was making really good progress right up till I tried to edit the embedded Struct. In it's simplified form it looks like this ...
struct Group: Identifiable, Codable {
var id = UUID()
var name: String
var number: Int
var spaces: Bool
var businesses: [Business]
}
struct Business: Identifiable, Codable {
var id = UUID()
var name: String
var address: String
var space: Int
var enabled: Bool
}
These are used in a class with an Observable var that stored in User Defaults
class GroupSettings: ObservableObject {
#Published var groups = [Group]() {
didSet {
UserDefaults.standard.set(try? PropertyListEncoder().encode(groups), forKey: "groups")
}
}
init() {
if let configData = UserDefaults.standard.value(forKey: "groups") as? Data {
if let userDefaultConfig = try?
PropertyListDecoder().decode(Array<Group>.self, from: configData){
groups = userDefaultConfig
}
}
}
}
Its passed in to my initial view and then I'm wanting to make an "Edit Detail" screen. When it gets to the edit detail screen, I can display the Business information in a Text display but I can't get it to working a TextField, it complains about can't convert a to a Binding, but the name from the initial Struct works fine, similar issues with the Int ...
I pass a Group from the first view which has the array of Groups in to the detail screen with the #Binding property ...
#Binding var group: Group
var body: some View {
TextField("", text: $group.name) <---- WORKS
List {
ForEach(self.group.businesses){ business in
if business.enabled {
Text(business.name) <---- WORKS
TextField("", business.address) <---- FAILS
TextField("", value: business.space, formatter: NumberFormatter()) <---- FAILS
} else {
Text("\(business.name) is disabled"
}
}
}
}
Hopefully I've explained my self well enough, and someone can point out the error of my ways. I did try embedding the 2nd Struct inside the first but that didn't help.
Thanks in advance!
You could use indices inside the ForEach and then still use $group and accessing the index of the businesses via the index like that...
List {
ForEach(group.businesses.indices) { index in
TextField("", text: $group.businesses[index].address)
}
}
An alternative solution may be to use zip (or enumerated) to have both businesses and its indices:
struct TestView: View {
#Binding var group: Group
var body: some View {
TextField("", text: $group.name)
List {
let items = Array(zip(group.businesses.indices, group.businesses))
ForEach(items, id: \.1.id) { index, business in
if business.enabled {
Text(business.name)
TextField("", text: $group.businesses[index].address)
} else {
Text("\(business.name) is disabled")
}
}
}
}
}
I'm developing a simple SwiftUI app in Xcode 11. I want to have a form that loops through multiple user input strings and displays a form with a button. When the user presses the button it modifies the input value - specifically increment or decrement it.
However when passing an array of references like UserInput().foo where UserInput is a published observable object I cannot modify the value inside a ForEach because the ForEach is passed a copy as oppose to the original reference (at least that's my basic understanding). How do I then try to achieve it? I read about inout and everybody says to avoid it but surely this must be a relatively common issue.
I've made an simple example of what I'm trying to do but I can't quite work it out:
import SwiftUI
class UserInput: ObservableObject {
#Published var foo: String = ""
#Published var bar: String = ""
}
struct ContentView: View {
#ObservedObject var input = UserInput()
var body: some View {
LoopInputs()
}
func LoopInputs() -> AnyView?{
var userinputs = [
[UserInput().foo, "Foo"],
[UserInput().bar, "Bar"]
]
var inputs: some View{
VStack(){
ForEach(userinputs, id: \.self){userinput in
Text("\(userinput[1]): \(String(userinput[0]))")
Button(action: {
increment(input: String(userinput[0]))
}){
Text("Increase")
}
}
}
}
return AnyView(inputs)
}
func increment(input: String){
var lead = Int(input) ?? 0
lead += 1
// input = String(lead)
}
}
As I understood, when adding a value to userinputs, the ForEach values doesn't change.
Well, if that's the case, first of all, you could try creating a struct and in it, you declare foo and bar, then just declare a variable of type the struct. It'll look like this:
struct Input: Identifiable {
var id = UUID()
var foo: String
var bar: String
}
class UserInput: ObservableObject {
#Published var inputs: [Input] = [Input]()
}
//ContentView
struct ContentView: View {
#ObservedObject var input = UserInput()
var body: some View {
LoopInputs()
}
func LoopInputs() -> AnyView? {
var inputs: some View {
VStack {
ForEach(input.inputs) { userinput in
Text("\(userinput.bar): \(String(userinput.foo))")
Button(action: {
increment(input: String(userinput.foo))
}) {
Text("Increase")
}
}
}
}
return AnyView(inputs)
}
func increment(input: String) {
var lead = Int(input) ?? 0
lead += 1
// input = String(lead)
}
}
Wouldn't this be easier and more elegant?
I've got an app that gets a list of vehicles from a REST backend server. It then uses that list to build a list of vehicles that can be tapped to show the details about one of them:
#State private var selectedVehicle: Vehicle?
#Binding var vehicles: [Vehicle]
List {
NavigationView {
ForEach( vehicles ) { vehicle in
NavigationLink( destination: VehicleDetailScreen( vehicle: vehicle ),
tag: vehicle,
selection: self.$selectedVehicle ) {
Text( vehicle.name )
}
}
}
}
struct VehicleDetailScreen: View {
var vehicle: Vehicle
var body: some View {
// Lots of rendering code omitted
}
}
So far, so good. This works nicely. The problem arises when we fetch updated information from the server. Updating the bound vehicles property works great for updating the list. But the detail screen is still showing data that's no longer relevant.
My first thought was just to pop the detail view off of the NavigationView. Unfortunately, SwiftUI doesn't provide any reliable way that I can find to do this in a two-column view on the iPad.
My next thought was that we needed to pass the vehicle in to VehicleDetailScreen as a #Binding too so that we can update it. But this is tough to do as well because we would need a reference to that binding so that we can cram updated values into it. The only way I can think of to do that would be to rework our network and model object code entirely so that it works like CoreData, keeping objects in memory and updating them with new values from the server, rather than generating new objects. This would be a good deal of effort, and obviously isn't something I'm keen to do if there's another option.
So I'm kind of stuck on this. Any thoughts/ideas/suggestions are very welcome!
Perhaps the concept of #Binding is somewhat confusing. From a #State var (parent view), to #Binding var (child view).
A struct Hashable to facilitate and reorder the elements of the array [Vehicle].
Something like this:
struct Vehicle: Hashable {
var name:String
//var otherItem: Any
}
struct ContentView: View {
#State var vehicle: Vehicle //the struct of your REST
#State var vehicles: [Vehicle] // the array of your REST
var body: some View {
List {
NavigationView {
ForEach(vehicles, id:\.self) { item in // loop the array to get every single item conform to the struct
NavigationLink( destination: VehicleDetailScreen(vehicle: self.$vehicle)) { // here to pass the binding
Text("\(self.vehicle.name)")
}
}
}
}
}
}
//detail view
struct VehicleDetailScreen: View {
#Binding var vehicle: Vehicle // here the binding
var body: some View {
Text("\(vehicle.name)")
}
}
If you want your detail views to update when data changes, you will have to make use of bindings.
As far as architecture goes, I would suggest to create so called Stores that hold data which can be used in multiple views. This, in combination with some static provider for Stores, makes it that you can easily access and modify data anywhere, and let your views update automatically.
When using UIKit, you would manually refresh data by calling reloadTable for instance. In SwiftUI this is not done. You could hypothetically manually trigger the view to update, but I would advice against this, as it is not the way SwiftUI was intended.
I've modified your code to show an example of this:
class StoreProvider {
static let carStore = CarStore()
}
class CarStore: ObservableObject {
#Published var vehicles: [Vehicle] = [Vehicle(id: "car01", name: "Porsche", year: 2016), Vehicle(id: "car02", name: "Lamborghini", year: 2002)]
}
struct Vehicle: Identifiable, Hashable {
let id: String
var name: String
var year: Int
}
struct CarOverview: View {
#ObservedObject var store = StoreProvider.carStore
#State var selectedVehicle: Vehicle?
var body: some View {
NavigationView {
List {
ForEach(store.vehicles.indices) { vehicleIndex in
NavigationLink(destination: VehicleDetailScreen(vehicle: self.$store.vehicles[vehicleIndex])) {
Text(self.store.vehicles[vehicleIndex].name)
}.onTapGesture {
self.selectedVehicle = self.store.vehicles[vehicleIndex]
}
}
}
}
}
}
struct VehicleDetailScreen: View {
#Binding var vehicle: Vehicle
func updateValues() {
vehicle.year = Int.random(in: 1990..<2020)
}
var body: some View {
VStack {
Text(vehicle.name)
Text("Year: ") + Text(vehicle.year.description)
}.onTapGesture(perform: updateValues)
}
}
I have just begun learning Swift (and even newer at Swift UI!) so apologies if this is a newbie error.
I am trying to write a very simple programme where a user chooses someone's name from a picker and then sees text below that displays a greeting for that person.
But, the bound var chosenPerson does not update when a new value is picked using the picker. This means that instead of showing a greeting like "Hello Harry", "Hello no-one" is shown even when I've picked a person.
struct ContentView: View {
var people = ["Harry", "Hermione", "Ron"]
#State var chosenPerson: String? = nil
var body: some View {
NavigationView {
Form {
Section {
Picker("Choose your favourite", selection: $chosenPerson) {
ForEach ((0..<people.count), id: \.self) { person in
Text(self.people[person])
}
}
}
Section{
Text("Hello \(chosenPerson ?? "no-one")")
}
}
}
}
}
(I have included one or two pieces of the original formatting in case this is making a difference)
I've had a look at this question, it seemed like it might be a similar problem but adding .tag(person) to Text(self.people[person])did not solve my issue.
How can I get the greeting to show the picked person's name?
Bind to the index, not to the string. Using the picker, you are not doing anything that would ever change the string! What changes when a picker changes is the selected index.
struct ContentView: View {
var people = ["Harry", "Hermione", "Ron"]
#State var chosenPerson = 0
var body: some View {
NavigationView {
Form {
Section {
Picker("Choose your favourite", selection: $chosenPerson) {
ForEach(0..<people.count) { person in
Text(self.people[person])
}
}
}
Section {
Text("Hello \(people[chosenPerson])")
}
}
}
}
}
The accepted answer is right if you are using simple arrays, but It was not working for me because I was using an array of custom model structs with and id defined as string, and in this situation the selection must be of the same type as this id.
Example:
struct CustomModel: Codable, Identifiable, Hashable{
var id: String // <- ID of type string
var name: String
var imageUrl: String
And then, when you are going to use the picker:
struct UsingView: View {
#State private var chosenCustomModel: String = "" //<- String as ID
#State private var models: [CustomModel] = []
var body: some View {
VStack{
Picker("Picker", selection: $chosenCustomModel){
ForEach(models){ model in
Text(model.name)
.foregroundColor(.blue)
}
}
}
Hope it helps somebody.