IOS manually turn off cellular data, it takes a long time to trigger onDone

[cookie-session]

@OverRide
void initState() {
super.initState();
_webSocket = IOWebSocketChannel.connect("ws://xxxxxx");
_webSocket!.stream.listen((data){
debugPrint(data);
}, onError: (e){
WebSocketChannelException ex = e;
debugPrint('---ex------${ex.message}');
}, onDone: (){
//IOS trigger has a delay of more than a few minutes
//Android everything is ok
debugPrint("2222");
});
}

[cookie-session]

[✓] Flutter (Channel stable, 2.5.3, on macOS 11.6.1 20G224 darwin-x64, locale
zh-Hans-CN)
[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.2)
[✓] Xcode - develop for iOS and macOS
[✓] Chrome - develop for the web
[✓] Android Studio (version 3.6)
[✓] Connected device (2 available)

[luckiers]

try pingInterval

[GoodMorrrrning]

How can we use pingInterval with WebSocketChannel ?
i have this :

WebSocketChannel channel = WebSocketChannel.connect(
   Uri.parse('ws://chat.something.fr'), 
 );