How to present a view after a request with URLSession in SwiftUI? - ios

Question

I want to present a view after I receive the data from a request, something like this
var body: some View {
VStack {
Text("Company ID")
TextField($companyID).textFieldStyle(.roundedBorder)
URLSession.shared.dataTask(with: url) { (data, _, _) in
guard let data = data else { return }
DispatchQueue.main.async {
self.presentation(Modal(LogonView(), onDismiss: {
print("dismiss")
}))
}
}.resume()
}
}

Answer 1

Business logic mixed with UI code is a recipe for trouble.
You can create a model object as a #ObjectBinding as follows.
class Model: BindableObject {
var didChange = PassthroughSubject<Void, Never>()
var shouldPresentModal = false {
didSet {
didChange.send(())
}
}
func fetch() {
// Request goes here
// Edit `shouldPresentModel` accordingly
}
}
And the view could be something like...
struct ContentView : View {
#ObjectBinding var model: Model
#State var companyID: String = ""
var body: some View {
VStack {
Text("Company ID")
TextField($companyID).textFieldStyle(.roundedBorder)
if (model.shouldPresentModal) {
// presentation logic goes here
}
}.onAppear {
self.model.fetch()
}
}
}
The way it works:
When the VStack appears, the model fetch function is called and executed
When the request succeeds shouldPresentModal is set to true, and a message is sent down the PassthroughSubject
The view, which is a subscriber of that subject, knows the model has changed and triggers a redraw.
If shouldPresentModal was set to true, additional UI drawing is executed.
I recommend watching this excellent WWDC 2019 talk:
Data Flow Through Swift UI
It makes all of the above clear.

Answer 2

I think you can do smth like that:
var body: some View {
VStack {
Text("Company ID")
}
.onAppear() {
self.loadContent()
}
}
private func loadContent() {
let url = URL(string: "https://your.url")!
URLSession.shared.dataTask(with: url) { (data, _, _) in
guard let data = data else { return }
DispatchQueue.main.async {
self.presentation(Modal(ContentView(), onDismiss: {
print("dismiss")
}))
}
}.resume()
}