[bug][ios] UiKitView and url_launcher conflict

bugUiKitView.dart

import 'package:flutter/material.dart';
import 'package:webview_flutter/webview_flutter.dart';
import 'package:url_launcher/url_launcher.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  MyHomePage({Key key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Flutter Demo Home Page'),
      ),
      backgroundColor: Colors.blue,
      body: Column(
        children: <Widget>[
          Container(
            height: 400,
            child: WebView(
              initialUrl: "https://google.com/"
            ),
          ),
          RaisedButton(
            child: Text("launch url"),
            onPressed: () => _launchUrl('https://flutter.dev'),
          ),
          RaisedButton(
            child: Text("new page"),
            onPressed: () => _pushPage(context),
          )
        ]       
      )
    );
  }
}



class MySecondPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Column(
      children: <Widget>[
        RaisedButton(
          onPressed: () => _launchUrl('https://flutter.dev'),
          child: Text('Launch url'),
        ),
        RaisedButton(
          child: Text("new page"),
          onPressed: () => _pushPage(context),
        )
      ]
    );
  }
}


void _launchUrl(String url) async {
  if (await canLaunch(url)) {
    await launch(url, forceSafariVC: true);
  } else {
    throw 'Could not launch $url';
  }
}

void _pushPage(BuildContext context) {
  Navigator.of(context).push(
    MaterialPageRoute<void>(
      builder: (_) => Scaffold(
        appBar: AppBar(title: Text("Tittle")),
        body: MySecondPage(),
      )
    )
  );
}

tempFixUiKitView.dart

import 'package:flutter/material.dart';
import 'package:webview_flutter/webview_flutter.dart';
import 'package:url_launcher/url_launcher.dart';
import 'dart:async';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key}) : super(key: key);

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {

  bool _showWebView = true;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Flutter Demo Home Page'),
      ),
      backgroundColor: Colors.blue,
      body: Column(
        children: <Widget>[
          Container(
            width: double.infinity,
            height: 400,
            child: _showWebView ? WebView(
              initialUrl: "https://google.com/"
            ) : Text("Waiting"),
          ),
          RaisedButton(
            child: Text("launch url"),
            onPressed: () => _launchUrl('https://flutter.dev'),
          ),
          RaisedButton(
            child: Text("new page"),
            onPressed: () async {
              Timer(Duration(milliseconds: 500), (){
                setState(() {
                  _showWebView = false;
                });
              });
              await _pushPage(context);
              setState(() {
                _showWebView = true;
              });
            },
          )
        ]       
      )
    );
  }
}



class MySecondPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Column(
      children: <Widget>[
        RaisedButton(
          onPressed: () => _launchUrl('https://flutter.dev'),
          child: Text('Launch url'),
        ),
        RaisedButton(
          child: Text("new page"),
          onPressed: () => _pushPage(context),
        )
      ]
    );
  }
}


void _launchUrl(String url) async {
  if (await canLaunch(url)) {
    await launch(url, forceSafariVC: true);
  } else {
    throw 'Could not launch $url';
  }
}

Future<void> _pushPage(BuildContext context) {
  return Navigator.of(context).push(MaterialPageRoute<void>(
    builder: (_) => Scaffold(
      appBar: AppBar(title: Text("Tittle")),
      body: MySecondPage(),
    ),
  ));
}