Flutter don't update UI from iOS using setState() method - ios

Question

I am invoking a method from native Swift code by using the platform channel like this:
channel.invokeMethod(METHOD_NAME, arguments: STRING_ARGUMENT)
in my Flutter class I handle the respective method call by using a callback
platform.setMethodCallHandler(_receiveFromHost);
The setMethodCallHandler() requires the callback to return a Future and I set state in _receiveFromHost method in Dart.
Problem is that my UI is not updated when Swift invokes the callback. Why?
call.method catch method string, state is set, but UI don't update.
video
This is my code in Swift:
let flutterEngine = (UIApplication.shared.delegate as! AppDelegate).flutterEngine
let flutterViewController = FlutterViewController(engine: flutterEngine!, nibName: nil, bundle: nil)
let channel = FlutterMethodChannel(name: "flutter_apple_pay", binaryMessenger: flutterViewController.binaryMessenger)
channel.invokeMethod("sendDidFinishAdding", arguments: "payment success")
And this is my code in Flutter:
import 'package:flutter/material.dart';
import 'dart:async';
import 'package:flutter/services.dart';
import 'dart:convert';
void main() => runApp(new MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return new MaterialApp(
home: new HomePage(),
);
}
}
class HomePage extends StatelessWidget {
#override
Widget build(BuildContext context) {
return new Scaffold(
appBar: new AppBar(
title: const Text("Native Code from Dart"),
),
body: new MyHomePage(title: ""),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
#override
_MyHomePageState createState() => new _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
String _state = "Waiting results...";
static const platform = const MethodChannel("flutter_apple_pay");
_MyHomePageState() {
platform.setMethodCallHandler(_receiveFromHost);
}
// #override
// void initState() {
// platform.setMethodCallHandler(_receiveFromHost);
// super.initState();
// }
Future<dynamic> _receiveFromHost(MethodCall call) async {
List certificatesBase64Encoded;
String nonceBase64Encoded;
String nonceSignatureBase64Encoded;
String state;
try {
print(call.method);
if (call.method == "sendGenerateRequestWithData") {
final String data = call.arguments;
final jData = jsonDecode(data);
certificatesBase64Encoded = jData['certificatesBase64Encoded'];
nonceBase64Encoded = jData['nonceBase64Encoded'];
nonceSignatureBase64Encoded = jData['nonceSignatureBase64Encoded'];
print(certificatesBase64Encoded);
print(nonceBase64Encoded);
print(nonceSignatureBase64Encoded);
state = "sendGenerateRequestWithData";
platform.invokeMethod("SendTokenizationData", "TokenizationDataString");
} else if (call.method == "sendDidFinishAdding") {
final String result = call.arguments;
print(result);
state = result;
}
} on PlatformException catch (e) {
print(e);
}
setState(() {
_state = state;
});
print(_state);
}
Future<void> _checkCardState() async {
String cardState;
const primaryAccountIdentifiers = ["a", "b"];
try {
final String result = await platform.invokeMethod(
"checkCardState", primaryAccountIdentifiers);
cardState = result;
} on PlatformException catch (e) {
cardState = "Failed to Invoke: '${e.message}'.";
}
setState(() {
_state = cardState;
});
}
Future<void> _startApplePay() async {
const _cardNetwork = "cn/AMEX";
const _cardHolderName = "pero peric";
const _primaryAccountIdentifier = "a";
const _primaryAccountSuffix = "1234";
const _localizedDescription = "AMEX";
Map<String, dynamic> resultMap = Map();
resultMap['cardNetwork'] = _cardNetwork;
resultMap['cardHolderName'] = _cardHolderName;
resultMap['primaryAccountIdentifier'] = _primaryAccountIdentifier;
resultMap['primaryAccountSuffix'] = _primaryAccountSuffix;
resultMap['localizedDescription'] = _localizedDescription;
platform.invokeMethod("startApplePay", resultMap);
}
#override
Widget build(BuildContext context) {
return Material(
child: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: [
ElevatedButton(
child: Text('Check Card State'),
onPressed: _checkCardState,
),
ElevatedButton(
child: Text('Start Apple Pay'),
onPressed: _startApplePay,
),
Text(_state),
],
),
),
);
}
}
Thanks!