Simplest way to pass #Published data to a Textfield()? - swiftui

Question

Scenario:
I'm using an Observable Class to acquire data from the network.
In this case some elementary weather data.
Problem:
I don't know how to display this data in the calling View.
For the time-being, I merely am trying to populate a Textfield (and worry about more-eleborate layout later).
I get the following:
.../StandardWeatherView.swift:22:13: Cannot invoke initializer for
type 'TextField<_>' with an argument list of type '(Text, text:
Sample?)'
Here's is my calling View which is the receiver of #ObservedObject data:
import SwiftUI
struct StandardWeatherView: View {
#EnvironmentObject var settings: Settings
#ObservedObject var standardWeatherReportLoader = StandardWeatherReportLoader()
init() {
self.standardWeatherReportLoader.doStandard()
}
var body: some View {
ZStack {
Color("FernGreen").edgesIgnoringSafeArea(.all)
TextField(Text("Weather Data"), text: standardWeatherReportLoader.weatherReport)
}
}
}
struct StandardWeatherView_Previews: PreviewProvider {
static var previews: some View {
StandardWeatherView()
}
}
Here's the publisher, acquiring data:
import Foundation
class StandardWeatherReportLoader: ObservableObject {
#Published var networkMessage: String?
#Published var hasAlert = false
#Published var weatherReport: Sample?
#Published var hasReport = false
func doStandard() {
let url = EndPoint.weather.path()
var request = URLRequest(url: EndPoint.weather.path()!)
request.httpMethod = "GET"
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
let task = URLSession.shared.dataTask(with: url!) { (data: Data?, _: URLResponse?, error: Error?) -> Void in
DispatchQueue.main.async {
guard error == nil else {
self.networkMessage = error?.localizedDescription
self.hasAlert = true
return
}
do {
let decoder = JSONDecoder()
decoder.keyDecodingStrategy = .convertFromSnakeCase
let result = try decoder.decode(Sample.self, from: data!)
self.weatherReport = result
self.hasReport = true
print("\n Standard Weather ----------------")
print(#function, "line: ", #line, "Result: ",result)
print("\n")
} catch let error as NSError {
print(error)
}
}
}
task.resume()
}
}
What's the simplest way of passing a string of data to the View via #Published var?
Log:
Standard Weather ---------------- doStandard() line: 38 Result:
Sample(coord: DataTaskPubTab.Coord(lon: -0.13, lat: 51.51), weather:
[DataTaskPubTab.Weather(id: 300, main: "Drizzle", description: "light
intensity drizzle")], base: "stations", main:
DataTaskPubTab.Main(temp: 280.32, pressure: 1012, humidity: 81,
tempMin: 279.15, tempMax: 281.15), visibility: 10000, wind:
DataTaskPubTab.Wind(speed: 4.1, deg: 80), clouds:
DataTaskPubTab.Clouds(all: 90), dt: 1485789600.0, id: 2643743, name:
"London")
But I'm getting nil at the TextField:
(lldb) po standardWeatherReportLoader.weatherReport nil

Answer 1

One option is to set a binding within your body to track whenever the TextField has updated. From within this binding, you can then edit your Published variable as you wish:
#ObservedObject var reportLoader = StandardWeatherReportLoader()
var body: some View {
// Binding to detect when TextField changes
let textBinding = Binding<String>(get: {
self.reportLoader.networkMessage
}, set: {
self.reportLoader.networkMessage = $0
})
// Return view containing the text field
return VStack {
TextField("Enter the Network Message", text: textBinding)
}
}
Edit: Also in your original post, you were passing an object of optional type Sample into the TextField which was expecting a binding String type which could cause some issues.