Observing changes #FocusState variable not working as expected - swiftui

Question

I want to validate the user's changes in a specific textfield and thus need to hook in when this textfield loses focus. I am using this year's introduced .focused(_:equals:) modifier with an enum and a #FocusState.
Observing my optional #FocusState var, which is nil when the screen first loads, with .onChange(of:perform:), this is only called once, when #FocusState changes from nil to a value–but not when it changes to another enum value.
The latter is expected though, and once this happens I could check what the previous field was–at least that's my approach for now.
Why is this approach not working–and is there a better way to go about this?
struct FocusView: View {
#State private var nameLast = "Ispum"
#State private var phoneNumber = "[phone]"
enum Field {
case nameLast
case phoneNumber
}
#FocusState private var focusedField: Field?
#State private var prevFocusedField: Field?
var body: some View {
VStack {
TextField("Last Name", text: $nameLast)
.focused($focusedField, equals: .nameLast)
TextField("Phone Number", text: $phoneNumber, prompt: Text(""))
.focused($focusedField, equals: .nameLast)
}
.onChange(of: focusedField) { newFocusField in
//only called once–when `focusedField` changes its state from `nil` to a value
print("Old value: \(prevFocusedField)")
print("New value: \(focusedField)")
if prevFocusedField == .phoneNumber {
//Validation
}
prevFocusedField = newFocusField
}
.textFieldStyle(.roundedBorder)
.padding()
}
}

Answer 1

There is a typo in your code (probably copy-paste)
TextField("Phone Number", text: $phoneNumber, prompt: Text(""))
.focused($focusedField, equals: .nameLast) // << here !!
you should use different value for second field:
VStack {
TextField("Last Name", text: $nameLast)
.focused($focusedField, equals: .nameLast)
TextField("Phone Number", text: $phoneNumber, prompt: Text(""))
.focused($focusedField, equals: .phoneNumber) // << fix !!
}
Tested with Xcode 13 / iOS 15