Share Data Binding Between Class and Struct View - swift

Question

For example, when I get data from API success or unsuccess I would like to show Alert but Alert there need isPresented type is Binding that's why I want to use concept Share Data as Binding between class and View is possible or have another way to do please help thanks advance.

Answer 1

#Published properties work well for sharing data between ObservableObjects and Views.
For example:
class ViewModel : ObservableObject {
struct APIError : Identifiable {
var id = UUID()
var message : String
}
#Published var error : APIError?
func apiCall() {
DispatchQueue.main.asyncAfter(deadline: .now() + 1) {
self.error = APIError(message: "Error message")
}
}
}
struct ContentView : View {
#StateObject var viewModel = ViewModel()
var body: some View {
VStack {
Text("Hello, world!")
.alert(item: $viewModel.error) { item in
Alert(title: Text(item.message))
}
}
.onAppear {
viewModel.apiCall()
}
}
}
You could also do this with a custom Binding, but it's a little messier. The above example would definitely be my go-to.
class ViewModel : ObservableObject {
#Published var errorMessage : String?
var alertBinding : Binding<Bool> {
.init {
self.errorMessage != nil
} set: { newValue in
if !newValue { self.errorMessage = nil }
}
}
func apiCall() {
DispatchQueue.main.asyncAfter(deadline: .now() + 1) {
self.errorMessage = "Error!"
}
}
}
struct ContentView : View {
#StateObject var viewModel = ViewModel()
var body: some View {
VStack {
Text("Hello, world!")
.alert(isPresented: viewModel.alertBinding) {
Alert(title: Text(viewModel.errorMessage ?? "(unknown)"))
}
}
.onAppear {
viewModel.apiCall()
}
}
}