【Flutter/Dart】iOSアプリにgoogle_mobile_adsを使うとCocoaPods関連のエラーで起動しない

Question

FlutterでiOSアプリにgoogle_mobile_adsを使うと、以下のようにCocoaPods関連のエラーで起動しません。
解決方法を教えてもらえないでしょうか。

●エラー

Launching lib/main.dart on iPhone 11 in debug mode...
Running Xcode build...
Xcode build done.                                           11.3s
Failed to build iOS app
Error output from Xcode build:
↳
    objc[42521]: Class AMSupportURLConnectionDelegate is implemented in both /usr/lib/libauthinstall.dylib (0x20c6bec10) and /System/Library/PrivateFrameworks/MobileDevice.framework/Versions/A/MobileDevice (0x122d802b8). One of the two will be used. Which one is undefined.
    objc[42521]: Class AMSupportURLSession is implemented in both /usr/lib/libauthinstall.dylib (0x20c6bec60) and /System/Library/PrivateFrameworks/MobileDevice.framework/Versions/A/MobileDevice (0x122d80308). One of the two will be used. Which one is undefined.
    ** BUILD FAILED **


Xcode's output:
↳
    Error: Cannot run with sound null safety, because the following dependencies
    don't support null safety:

     - package:google_mobile_ads

    For solutions, see https://dart.dev/go/unsound-null-safety

    Command PhaseScriptExecution failed with a nonzero exit code
    note: Using new build system
    note: Building targets in parallel
    note: Planning build
    note: Analyzing workspace
    note: Constructing build description
    note: Build preparation complete
    /Users/flutter/adtest/ios/Pods/Pods.xcodeproj: warning: The iOS Simulator deployment target 'IPHONEOS_DEPLOYMENT_TARGET' is set to 8.0, but the range of supported deployment target versions is 9.0 to 14.5.99. (in target 'Flutter' from project 'Pods')

Could not build the application for the simulator.
Error launching application on iPhone 11.

●実行環境

Flutter 2.2.2 • channel stable • https://github.com/flutter/flutter.git
Framework • revision d79295af24 (8 days ago) • 2021-06-11 08:56:01 -0700
Engine • revision 91c9fc8fe0
Tools • Dart 2.13.3
OS:Mac 11.4 (M1 MacBook Air)
IDE:Android Studio 4.2.1

●main.dart

import 'package:flutter/material.dart';
import 'package:google_mobile_ads/google_mobile_ads.dart';
import 'dart:io';
void main() {
  //以下の二行を追加
  WidgetsFlutterBinding.ensureInitialized();
  MobileAds.instance.initialize();
  //追加ここまで
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key? key, required this.title}) : super(key: key);

  final String title;

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

class _MyHomePageState extends State<MyHomePage> {
  // This widget is the root of your application.
  final BannerAd myBanner = BannerAd(
    adUnitId: getTestAdBannerUnitId(),
    size: AdSize.banner,
    request: AdRequest(),
    listener: AdListener(),
  );
  @override
  Widget build(BuildContext context) {
    myBanner.load();

    final AdWidget adWidget = AdWidget(ad: myBanner);

    final Container adContainer = Container(
      alignment: Alignment.center,
      child: adWidget,
      width: myBanner.size.width.toDouble(),
      height: myBanner.size.height.toDouble(),
    );
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(

        child: Column(

          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            adContainer,
          ],
        ),
      ),
// This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}

//プラットホームごとのテスト広告IDを取得するメソッドをどこかに配置してください。
String getTestAdBannerUnitId(){
  String testBannerUnitId = "";
  if(Platform.isAndroid) {
    // Android のとき
    testBannerUnitId = "ca-app-pub-3940256099942544/6300978111";
  } else if(Platform.isIOS) {
    // iOSのとき
    testBannerUnitId = "ca-app-pub-3940256099942544/2934735716";
  }
  return testBannerUnitId;
}

Podfile
※2行目でiOSのバージョンを11に指定

# Uncomment this line to define a global platform for your project
platform :ios, '11.0'

# CocoaPods analytics sends network stats synchronously affecting flutter build latency.
ENV['COCOAPODS_DISABLE_STATS'] = 'true'

project 'Runner', {
  'Debug' => :debug,
  'Profile' => :release,
  'Release' => :release,
}

def flutter_root
  generated_xcode_build_settings_path = File.expand_path(File.join('..', 'Flutter', 'Generated.xcconfig'), __FILE__)
  unless File.exist?(generated_xcode_build_settings_path)
    raise "#{generated_xcode_build_settings_path} must exist. If you're running pod install manually, make sure flutter pub get is executed first"
  end

  File.foreach(generated_xcode_build_settings_path) do |line|
    matches = line.match(/FLUTTER_ROOT\=(.*)/)
    return matches[1].strip if matches
  end
  raise "FLUTTER_ROOT not found in #{generated_xcode_build_settings_path}. Try deleting Generated.xcconfig, then run flutter pub get"
end

require File.expand_path(File.join('packages', 'flutter_tools', 'bin', 'podhelper'), flutter_root)

flutter_ios_podfile_setup

target 'Runner' do
  use_frameworks!
  use_modular_headers!

  flutter_install_all_ios_pods File.dirname(File.realpath(__FILE__))
end

post_install do |installer|
  installer.pods_project.targets.each do |target|
    flutter_additional_ios_build_settings(target)
  end
end

●Runner.xcworkspace
※Deployment Targetを11に変更

●pubspec.yaml

name: testapp
description: A new Flutter project.
publish_to: 'none' # Remove this line if you wish to publish to pub.dev
version: 1.0.0+1

environment:
  sdk: '>=2.12.0 <3.0.0'

dependencies:
  flutter:
    sdk: flutter

  google_mobile_ads:
  cupertino_icons: ^1.0.2

dev_dependencies:
  flutter_test:
    sdk: flutter
flutter:
  uses-material-design: true

Comments

[hoshi-takanori]

その記事のコメント欄で聞いてみれば良いのでは。

Answer 1

iOS Deployment Targetの設定が低すぎるんではないでしょうか。
Runner.xcworkspaceを開いてDeployment Target上げたり、Podfileの上部をいじってみてください。

Comments

[tantan1]

ご回答ありがとうございます。Runner.xcworkspaceのDeployment TargetやPodfileの2行目を9や11にバージョンを上げてみたのですがエラーが解消されませんでした。エラーメッセージが変わりましたので、記事内容も修正しております(ご教示いただいた変更作業も併せて追記しました)。エラーメッセージをみるとバージョン変更が反映されていないようにも見え、Android Studioを再起動してデバッグし直したりもしましたが変わりませんでした・・・。

[hiroshihorie]

あ、null safetyのエラーに変わってますね。これは—no-sound-null-safetyオプション付けてビルドするか、null safety対応パッケージを使えば解決すると思います。

[tantan1]

「flutter run --no-sound-null-safety」で実行できました。ありがとうございました。

[hiroshihorie]

✌????
--no-sound-null-safetyは無理やりnull safetyなしで実行するオプションなので長期的には完全にnull safetyに移行したほうが良いです。各種パッケージも移行中みたいですご確認ください。

[tantan1]

ありがとうございます。null safetyに移行できるよう、使用するパッケージについて考えます。