SwiftUI http request - swiftui

Question

I need to post a http request to login view (SwiftUI), my code follow
I have in HttpAuth.swift:
import Foundation
import Combine
struct ServerMessage: Decodable {
let res, message: String
}
class HttpAuth: ObservableObject {
let objectWillChange = PassthroughSubject<HttpAuth, Never>()
var authenticated = false {
didSet {
objectWillChange.send(self)
}
}
func postAuth(username: String, password: String) {
guard let url = URL(string: "http://mysite/loginswift.php") else { return }
let body: [String: String] = ["username": username, "password": password]
let finalBody = try! JSONSerialization.data(withJSONObject: body)
var request = URLRequest(url: url)
request.httpMethod = "POST"
request.httpBody = finalBody
request.setValue("application/json", forHTTPHeaderField: "Content-Type")
URLSession.shared.dataTask(with: request) { (data, response, error) in
guard let data = data else { return }
let resData = try! JSONDecoder().decode(ServerMessage.self, from: data)
print(resData.res)
if resData.res == "correct" {
DispatchQueue.main.async {
self.authenticated = true
}
}
}.resume()
}
}
And in ContentView.swift:
import SwiftUI
struct ContentView: View {
#State private var username: String = ""
#State private var password: String = ""
#State var manager = HttpAuth()
var body: some View {
VStack(alignment: .leading) {
if self.manager.authenticated {
Text("Correct!").font(.headline)
}
Text("Username")
TextField("placeholder", text: $username)
.textFieldStyle(RoundedBorderTextFieldStyle())
.border(Color.green)
.autocapitalization(.none)
Text("Password")
SecureField("placeholder", text: $password)
.textFieldStyle(RoundedBorderTextFieldStyle())
.border(Color.green)
Button(action: {
self.manager.postAuth(username: self.username, password: self.password)
}) {
HStack{
Spacer()
Text("Login")
Spacer()
}
.accentColor(Color.white)
.padding(.vertical, 10)
.background(Color.red)
.cornerRadius(5)
.padding(.horizontal, 40)
}
}.padding()
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
It works, i receive the answer from server but it doesn't update the ContentView, the 'self.manager.authenticated' in ContentView doesn't refresh from HttpAuth class.
This part of code doesn't work:
if self.manager.authenticated {
Text("Correct!").font(.headline)
}
The 'authenticated' still on false.
How can i fix it, thank you.

Answer 1

Although the accepted answer meets the objective I don't think it's the best way to do it because it implements #EnvironmentObject and it should be used for global application issues and not for the specific request of a view.
You can implement a "ViewModel" that is specific for the view, to do the work of the request and make the update of the variable.
Documentation: https://developer.apple.com/documentation/combine/observableobject
The implementation for your code would be like this, based on the changes suggested by #Chris:
This works in Xcode Version 11.2 (11B52)
HttpAuth.swif:
import Foundation
import SwiftUI
import Combine
class HttpAuth: ObservableObject {
#Published var authenticated = false
func postAuth(username: String, password: String) {
guard let url = URL(string: "http://mysite/loginswift.php") else { return }
let body: [String: String] = ["username": username, "password": password]
let finalBody = try! JSONSerialization.data(withJSONObject: body)
var request = URLRequest(url: url)
request.httpMethod = "POST"
request.httpBody = finalBody
request.setValue("application/json", forHTTPHeaderField: "Content-Type")
URLSession.shared.dataTask(with: request) { (data, response, error) in
guard let data = data else { return }
let resData = try! JSONDecoder().decode(ServerMessage.self, from: data)
print(resData.res)
if resData.res == "correct" {
DispatchQueue.main.async {
self.authenticated = true
}
}
}.resume()
}
}
ContentView.swift
import SwiftUI
struct ContentView: View {
#State private var username: String = ""
#State private var password: String = ""
#ObservedObject var manager = HttpAuth()
var body: some View {
VStack(alignment: .leading) {
if self.manager.authenticated {
Text("Correct!").font(.headline)
}
Spacer()
Text("Username")
TextField("placeholder", text: $username)
.textFieldStyle(RoundedBorderTextFieldStyle())
.border(Color.green)
.autocapitalization(.none)
Text("Password")
SecureField("placeholder", text: $password)
.textFieldStyle(RoundedBorderTextFieldStyle())
.border(Color.green)
Button(action: {
self.manager.postAuth(username: self.username, password: self.password)
}) {
HStack{
Spacer()
Text("Login")
Spacer()
}
.accentColor(Color.white)
.padding(.vertical, 10)
.background(Color.red)
.cornerRadius(5)
.padding(.horizontal, 40)
}
Spacer()
}.padding()
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
}

Answer 2

you can try this:
instead of
let objectWillChange = PassthroughSubject<HttpAuth, Never>()
var authenticated = false {
didSet {
objectWillChange.send(self)
}
}
use
#published var authenticated = false
and instead of
#State var manager = HttpAuth()
use
#EnvironmentObject private var manager: HttpAuth
and of course do this when calling ContentView:
ContentView().environmentObject(manager)
and somewhere outside class as global variable do
var manager = HttpAuth()
then it should work.