Updating swiftui text view after parsing json data - ios

Question

I have a function that goes out to an api and gets a stock price. I have the function returning a double and I can see the correct price print out to the console when I run the code. When I try to set that price to a variable inside the function so the function can return it, I just get 0.000 in the text view. Can someone tell me what I'm doing wrong? My code is below.
import SwiftUI
struct ListView: View {
var body: some View {
List {
HStack {
Text("Stock Price (15 Min. delay)")
Spacer()
Text("\(getStockPrice(stock: symbol))")
}
}
}
func getStockPrice(stock: String) -> Double {
var thePrice = Double()
guard let url = URL(string: "my url to get data") else {
fatalError("URL does not work!")
}
URLSession.shared.dataTask(with: url) { jsonData, _, _ in
guard let jData = jsonData else {return}
do {
if let json = try JSONSerialization.jsonObject(with: jData, options: []) as? [String: Any] {
if let pricer = json["latestPrice"] as? Double {
print(pricer)
thePrice = pricer
}
}
} catch let err {
print(err.localizedDescription)
}
}.resume()
return thePrice
}
}

Answer 1

You can update your UI with changing the #State variable, like in code below:
struct UpdatingPriceAsync: View {
#State var stockPrice: Double = 0.0
var body: some View {
List {
HStack {
Text("Stock Price (15 Min. delay)")
Spacer()
Text("\(stockPrice)")
.onAppear() {
self.updateStockPrice(stock: "something")
}
}
}
}
private func updateStockPrice(stock: String) {
DispatchQueue.main.asyncAfter(deadline: .now() + 1) { // sort of URL session task
DispatchQueue.main.async { // you need to update it in main thread!
self.stockPrice = 99.9
}
}
}
}