Flutter TLS Certificate Pinning (cannot bypass using SSLKillSwitch on iOS)

main.dart

import 'dart:io';
import 'package:dio/adapter.dart';
import 'package:dio/dio.dart';

void main() async {
  BaseOptions options = BaseOptions(
    baseUrl: "https://httpbin.org",
    connectTimeout: 3000,
    receiveTimeout: 3000,
  );

    Dio dio = Dio(options);

    // https://httpbin.org/ - leaf cert. 
    String certificate = '''
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
''';
    (dio.httpClientAdapter as DefaultHttpClientAdapter).onHttpClientCreate  = (client) {
        SecurityContext sc = new SecurityContext();
        sc.setTrustedCertificatesBytes(certificate.codeUnits);
        HttpClient httpClient = new HttpClient(context: sc);
        return httpClient;
    };

  try {
    Response resp = await dio.get(
      "/get",
      queryParameters: {"search": "dio"},
    );
    print("Response:");
    print("Status:\n${resp.statusCode}");
    print("Header:\n${resp.headers}");
    print("Data:\n${resp.data}");
  } catch (e) {
    print("Exception: $e");
  }
}