In iOS SimpleChatbot demo, add clarifying note to Audio Settings section header explaining that "(No selection = system default)".

Ideally we could add a row showing that the system default is selected, but this is OK as a short-term fix. Also, the presence of that row might suggest that "system default" is selectable, but it's not: this is currently a limitation in the Pipecat Client.

examples/simple-chatbot/client/ios/SimpleChatbot/views/settings/SettingsView.swift

@@ -13,7 +13,7 @@ struct SettingsView: View {
     var body: some View {
         NavigationView {
             Form {
-                Section(header: Text("Audio Settings")) {
+                Section {
                     List(model.availableMics, id: \.self.id.id) { mic in
                         Button(action: {
                             model.selectMic(mic.id)
@@ -27,6 +27,11 @@ struct SettingsView: View {
                             }
                         }
                     }
+                } header: {
+                    VStack(alignment: .leading) {
+                        Text("Audio Settings")
+                        Text("(No selection = system default)")
+                    }
                 }
                 Section(header: Text("Start options")) {
                     Toggle("Enable Microphone", isOn: $isMicEnabled)