SwiftUI: calling a method from nested view - ios

Question

I am pretty nw to SwiftUI, and to make my code more readable, I usually break my views into smaller views.
Let's say I have a viewModel, what is the best way to call a method of my viewModel from a nested view? Right now I am passing around my ViewModel as a parameter of every nested view, but I don't find it very optimal and clean...
Is there a way to notify MyMainView that the button of HeaderSubview was tapped ? Can I use Combine for example?
ViewModel
class MyViewModel {
func fetchSomeData() {
print("Fetching Some Data")
}
}
MainView
struct MyMainView: View {
var myViewModel = MyViewModel()
var body: some View {
HeaderView(viewModel: myViewModel)
}
}
struct HeaderView: View {
var viewModel: MyViewModel
var body: some View {
HeaderSubview(viewModel: viewModel)
}
}
struct HeaderSubview: View {
var viewModel: MyViewModel
var body: some View {
Button("Search") {
// I want to call my View Model method here
viewModel.fetchSomeData()
}
}
}

Answer 1

You can make your class ObservableObject and inject it as environment object, so any subview can use it and main view would be able to observe it.
Something like
class MyViewModel: ObservableObject {
#Published var loading = false
func fetchSomeData() {
loading = true
DispatchQueue.global(qos: .background).async {
print("Fetching Some Data")
// ... long activity here
DispatchQueue.main.async { [weak self] in
self?.loading = false
}
}
}
}
struct MyMainView: View {
#StateObject var myViewModel = MyViewModel()
var body: some View {
HeaderView().environmentObject(myViewModel)
if myViewModel.loading {
Text("Loading...")
}
}
}
struct HeaderView: View {
var body: some View {
HeaderSubview()
}
}
struct HeaderSubview: View {
#EnvironmentObject var viewModel: MyViewModel
var body: some View {
Button("Search") {
// I want to call my View Model method here
viewModel.fetchSomeData()
}
}
}