Zenn
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url_launcherを使ってハマった!

2023/01/17に公開
Flutter
tech

補足情報

処理の仕方が現在とは違っていたりというご意見をいただき動作検証をしました。
同じコードで動いてますけどね😅
2024/05/19~
https://github.com/sakurakotubaki/url_launcher_example

[コミットの履歴]
https://github.com/sakurakotubaki/url_launcher_example/commit/5645f39b5a587628012171c6b92d59ff4d05b878

Androidではnullになる?

WebページのリンクをFlutterのコードに貼り付けて、クリックしたら表示できる便利なpackageがあるのですが、iOSだとできるのに、Androidだと、nullのエラーが出てしまう🤔

今回使用したpackage

https://pub.dev/packages/url_launcher

解決方法

packageのGithubのexampleのAndroidManifest.xmlの設定見て見てみました。Readmeと比較すると端末へのアクセスを許可するコードを追加しないと、権限のエラーが出てしまうようです!

こちらですね。

<!-- The INTERNET permission is required for development. Specifically,
       flutter needs it to communicate with the running application
       to allow setting breakpoints, to provide hot reload, etc.
  -->
  <uses-permission android:name="android.permission.INTERNET"/>

コメントを翻訳すると

この英語を翻訳すると
<!-- The INTERNET permission is required for development. Specifically,
       flutter needs it to communicate with the running application
       to allow setting breakpoints, to provide hot reload, etc.
  -->
このように書かれていました
<!-- 開発にはINTERNETの許可が必要です。具体的には
       flutterは実行中のアプリケーションと通信するためにこれを必要とします。
       ブレークポイントの設定、ホットリロードの提供などのために必要です。
  -->

Readmeの追加するコード

example/android/app/src/main/AndroidManifest.xml
<!-- The INTERNET permission is required for development. Specifically,
       flutter needs it to communicate with the running application
       to allow setting breakpoints, to provide hot reload, etc.
  -->
  <uses-permission android:name="android.permission.INTERNET"/>

  <!--#docregion android-queries-->
  <!-- Provide required visibility configuration for API level 30 and above -->
  <queries>
    <!-- If your app checks for SMS support -->
    <intent>
      <action android:name="android.intent.action.VIEW" />
      <data android:scheme="sms" />
    </intent>
    <!-- If your app checks for call support -->
    <intent>
      <action android:name="android.intent.action.VIEW" />
      <data android:scheme="tel" />
    </intent>
    <!--#enddocregion android-queries-->
    <!-- The "https" scheme is only required for integration tests of this package.
         It shouldn't be needed in most actual apps, or show up in the README! -->
    <intent>
      <action android:name="android.intent.action.VIEW" />
      <data android:scheme="https" />
    </intent>
    <!--#docregion android-queries-->
  </queries>
  <!--#enddocregion android-queries-->

追加後

example/android/app/src/main/AndroidManifest.xml
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.url_launcher_app">
<!-- ここから -->
    <uses-permission android:name="android.permission.INTERNET"/>
<queries>
    <!-- If your app checks for SMS support -->
    <intent>
      <action android:name="android.intent.action.VIEW" />
      <data android:scheme="sms" />
    </intent>
    <!-- If your app checks for call support -->
    <intent>
      <action android:name="android.intent.action.VIEW" />
      <data android:scheme="tel" />
    </intent>
    <!--#enddocregion android-queries-->
    <!-- The "https" scheme is only required for integration tests of this package.
         It shouldn't be needed in most actual apps, or show up in the README! -->
    <intent>
      <action android:name="android.intent.action.VIEW" />
      <data android:scheme="https" />
    </intent>
    <!--#docregion android-queries-->
  </queries>
<!-- ここまで -->
   <application
        android:label="url_launcher_app"
        android:name="${applicationName}"
        android:icon="@mipmap/ic_launcher">
        <activity
            android:name=".MainActivity"
            android:exported="true"
            android:launchMode="singleTop"
            android:theme="@style/LaunchTheme"
            android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
            android:hardwareAccelerated="true"
            android:windowSoftInputMode="adjustResize">
            <!-- Specifies an Android theme to apply to this Activity as soon as
                 the Android process has started. This theme is visible to the user
                 while the Flutter UI initializes. After that, this theme continues
                 to determine the Window background behind the Flutter UI. -->
            <meta-data
              android:name="io.flutter.embedding.android.NormalTheme"
              android:resource="@style/NormalTheme"
              />
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
        <!-- Don't delete the meta-data below.
             This is used by the Flutter tool to generate GeneratedPluginRegistrant.java -->
        <meta-data
            android:name="flutterEmbedding"
            android:value="2" />
    </application>
</manifest>

iOSの設定はこちら

Readmeのコードを<dict>の下に貼り付ける

<key>LSApplicationQueriesSchemes</key>
<array>
  <string>sms</string>
  <string>tel</string>
</array>

追加後のコード

ios/Runner/info.plist
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
	<!-- ここから-->
	<key>LSApplicationQueriesSchemes</key>
<array>
  <string>sms</string>
  <string>tel</string>
</array>
	<!-- ここまで-->
	<key>CFBundleDevelopmentRegion</key>
	<string>$(DEVELOPMENT_LANGUAGE)</string>
	<key>CFBundleDisplayName</key>
	<string>Url Launcher App</string>
	<key>CFBundleExecutable</key>
	<string>$(EXECUTABLE_NAME)</string>
	<key>CFBundleIdentifier</key>
	<string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
	<key>CFBundleInfoDictionaryVersion</key>
	<string>6.0</string>
	<key>CFBundleName</key>
	<string>url_launcher_app</string>
	<key>CFBundlePackageType</key>
	<string>APPL</string>
	<key>CFBundleShortVersionString</key>
	<string>$(FLUTTER_BUILD_NAME)</string>
	<key>CFBundleSignature</key>
	<string>????</string>
	<key>CFBundleVersion</key>
	<string>$(FLUTTER_BUILD_NUMBER)</string>
	<key>LSRequiresIPhoneOS</key>
	<true/>
	<key>UILaunchStoryboardName</key>
	<string>LaunchScreen</string>
	<key>UIMainStoryboardFile</key>
	<string>Main</string>
	<key>UISupportedInterfaceOrientations</key>
	<array>
		<string>UIInterfaceOrientationPortrait</string>
		<string>UIInterfaceOrientationLandscapeLeft</string>
		<string>UIInterfaceOrientationLandscapeRight</string>
	</array>
	<key>UISupportedInterfaceOrientations~ipad</key>
	<array>
		<string>UIInterfaceOrientationPortrait</string>
		<string>UIInterfaceOrientationPortraitUpsideDown</string>
		<string>UIInterfaceOrientationLandscapeLeft</string>
		<string>UIInterfaceOrientationLandscapeRight</string>
	</array>
	<key>UIViewControllerBasedStatusBarAppearance</key>
	<false/>
	<key>CADisableMinimumFrameDurationOnPhone</key>
	<true/>
	<key>UIApplicationSupportsIndirectInputEvents</key>
	<true/>
</dict>
</plist>

アプリのコード

pubspec.yaml
name: url_launcher_app
description: A new Flutter project.

# The following line prevents the package from being accidentally published to
# pub.dev using `flutter pub publish`. This is preferred for private packages.
publish_to: 'none' # Remove this line if you wish to publish to pub.dev

# The following defines the version and build number for your application.
# A version number is three numbers separated by dots, like 1.2.43
# followed by an optional build number separated by a +.
# Both the version and the builder number may be overridden in flutter
# build by specifying --build-name and --build-number, respectively.
# In Android, build-name is used as versionName while build-number used as versionCode.
# Read more about Android versioning at https://developer.android.com/studio/publish/versioning
# In iOS, build-name is used as CFBundleShortVersionString while build-number is used as CFBundleVersion.
# Read more about iOS versioning at
# https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
# In Windows, build-name is used as the major, minor, and patch parts
# of the product and file versions while build-number is used as the build suffix.
version: 1.0.0+1

environment:
  sdk: '>=2.18.0 <3.0.0'

# Dependencies specify other packages that your package needs in order to work.
# To automatically upgrade your package dependencies to the latest versions
# consider running `flutter pub upgrade --major-versions`. Alternatively,
# dependencies can be manually updated by changing the version numbers below to
# the latest version available on pub.dev. To see which dependencies have newer
# versions available, run `flutter pub outdated`.
dependencies:
  flutter:
    sdk: flutter


  # The following adds the Cupertino Icons font to your application.
  # Use with the CupertinoIcons class for iOS style icons.
  cupertino_icons: ^1.0.2
  url_launcher: ^6.1.7

dev_dependencies:
  flutter_test:
    sdk: flutter

  # The "flutter_lints" package below contains a set of recommended lints to
  # encourage good coding practices. The lint set provided by the package is
  # activated in the `analysis_options.yaml` file located at the root of your
  # package. See that file for information about deactivating specific lint
  # rules and activating additional ones.
  flutter_lints: ^2.0.0

# For information on the generic Dart part of this file, see the
# following page: https://dart.dev/tools/pub/pubspec

# The following section is specific to Flutter packages.
flutter:

  # The following line ensures that the Material Icons font is
  # included with your application, so that you can use the icons in
  # the material Icons class.
  uses-material-design: true

  # To add assets to your application, add an assets section, like this:
  # assets:
  #   - images/a_dot_burr.jpeg
  #   - images/a_dot_ham.jpeg

  # An image asset can refer to one or more resolution-specific "variants", see
  # https://flutter.dev/assets-and-images/#resolution-aware

  # For details regarding adding assets from package dependencies, see
  # https://flutter.dev/assets-and-images/#from-packages

  # To add custom fonts to your application, add a fonts section here,
  # in this "flutter" section. Each entry in this list should have a
  # "family" key with the font family name, and a "fonts" key with a
  # list giving the asset and other descriptors for the font. For
  # example:
  # fonts:
  #   - family: Schyler
  #     fonts:
  #       - asset: fonts/Schyler-Regular.ttf
  #       - asset: fonts/Schyler-Italic.ttf
  #         style: italic
  #   - family: Trajan Pro
  #     fonts:
  #       - asset: fonts/TrajanPro.ttf
  #       - asset: fonts/TrajanPro_Bold.ttf
  #         weight: 700
  #
  # For details regarding fonts from package dependencies,
  # see https://flutter.dev/custom-fonts/#from-packages
main.dart
import 'package:flutter/material.dart';
import 'package:url_launcher/url_launcher.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

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

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('URL Launcher'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            IconButton(
                onPressed: () async {
                  final url = Uri.parse(
                    'https://www.youtube.com/',
                  );
                  if (await canLaunchUrl(url)) {
                    launchUrl(url);
                  } else {
                    // ignore: avoid_print
                    print("Can't launch $url");
                  }
                },
                icon: const Icon(
                  Icons.movie,
                  color: Colors.red,
                  size: 50.0,
                )),
          ],
        ),
      ),
    );
  }
}

スクリーンショット

YouTubeのリンクを貼り付けたので、ボタンを押すと、home画面へ移動します。


最後に

公式ドキュメントをまず見ましょうと聞きますが、分かりにくいこともある。
そんなときは、ブログやStackOverFlowを見るのですが、情報が古かったりするので、今回はReadmeを見ながらurl_launcherの技術記事を見て、比較しながら設定を行い動くアプリを作るところまで持っていきました。

参考にしたブログ

https://dev-yakuza.posstree.com/flutter/url_launcher/

Discussion