Display activity indicator while fetching api data - swift

Question

I'm filling this Picker with data from my api
var body: some View {
NavigationView {
Form {
Section(header: Text("Pesquisar Denúncia")) {
//some code...
Picker(selection: $tipoDenunciaSelecionada, label: Text("Tipo de Denúncia")) {
ForEach(tiposDenuncia, id: \.self) {item in
Text(item.nome ?? "")
}
}.onAppear(perform: carregarTipoDenuncia)
//some more code...
}
}
For fetch data, i made this func
func carregarTipoDenuncia() {
self.estaCarregando = true
let oCodigo_Entidade = UserDefaults.standard.integer(forKey: "codigoEntidade")
guard let url = URL(string: "url here") else {
print("Erro ao conectar")
return
}
let request = URLRequest(url: url)
let task = URLSession.shared.dataTask(with: request) {data, response, error in
let decoder = JSONDecoder()
if let data = data {
do {
let response = try decoder.decode([TipoDenunciaModel].self, from: data)
DispatchQueue.main.async {
self.tiposDenuncia = response
}
return
} catch {
print(error)
}
}
}
task.resume()
}
but now i dont know to display an indicator that the data is being downloaded.
I tried adding a state boolean variable and manipulating it after response to show/hide an actionsheet but it didnt worked, the actionsheet didnt disapear.
I need the user to select at least one of the options of this picker.
How can i display some indicator that the data is loading?

Answer 1

As you can show any view in body add a boolean #State variable with initial value true and show a ProgressView. After loading the data set the variable to false which shows the Picker.
Move the .onAppear modifier to after Form.
var body: some View {
#State private var isLoading = true
// #State private var tipoDenunciaSelecionada ...
NavigationView {
Form {
Section(header: Text("Pesquisar Denúncia")) {
//some code...
if isLoading {
HStack(spacing: 15) {
ProgressView()
Text("Loading…")
}
} else {
Picker(selection: $tipoDenunciaSelecionada, label: Text("Tipo de Denúncia")) {
ForEach(tiposDenuncia, id: \.self) {item in
Text(item.nome ?? "")
}
}
//some more code...
}.onAppear(perform: carregarTipoDenuncia)
}
}
}
let response = try decoder.decode([TipoDenunciaModel].self, from: data)
DispatchQueue.main.async {
self.tiposDenuncia = response
self.isLoading = false
}
...

Answer 2

You can use a determinate SwiftUI ProgressView, as seen here.
Example usage:
import SwiftUI
struct ActivityIndicator: View {
#State private var someVar: CGFloat = 0.0 //You'll need some sort of progress value from your request
var body: some View {
ProgressView(value: someVar)
}
}