flutter - 如何在 Flutter 中请求和检查权限

Question

当用户单击不允许时，我正在使用各种插件来获取用户数据、联系人、照片和相机，应用程序会静默。
当用户选中“不再询问”和“不允许”并再次进入应用程序时，我想向用户显示“询问权限”对话框。
目前，当用户选中不允许时，应用程序不再要求
我知道用户必须授予应用程序访问个人信息的权限，包括 当前位置 , 相机 , 日历 , 联系方式 , 媒体库 , 麦克风 , 传感器 , 演讲 和照片。尽管人们喜欢使用可以访问这些信息的应用程序的便利性，但他们也希望能够控制他们的私有(private)数据。例如，人们喜欢能够自动标记照片与他们的实际位置或找到附近的 friend ，但他们也希望选择禁用这些功能。
如何在 flutter 中再次请求用户许可？

Answer 1

为简单起见，我使用了位置权限。要请求另一个权限，只需将 location 替换为该权限。这里是 list of all permissions .
1.安卓设置:

将这些添加到 android/grade.properties文件:

android.useAndroidX=true
android.enableJetifier=true

在 android/app/build.gradle文件:

android {
  compileSdkVersion 30 // Set this to at least 30
  ...
}

添加权限到android/app/src/main/AndroidManifest.xml文件

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
  <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/> 
  ...
 </manifest>

2.iOS设置:

将此添加到 info.plist文件:

<key>NSLocationWhenInUseUsageDescription</key>
<string>App needs location permission to work</string>

添加 PERMISSION_LOCATION=1至Podfile :

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

    target.build_configurations.each do |config|
      config.build_settings['GCC_PREPROCESSOR_DEFINITIONS'] ||= [
        '$(inherited)',

        ## Add the following line.
         'PERMISSION_LOCATION=1'
      ]

    end
  end
end

3. flutter 设置:
将此添加到 pubspec.yaml文件:

permission_handler: ^8.0.0+2

主要工作:

检查权限:
检查位置(即 GPS)是否已打开。

final serviceStatus = await Permission.locationWhenInUse.serviceStatus;
bool isGpsOn = serviceStatus == ServiceStatus.enabled;

申请许可:

final status = await Permission.locationWhenInUse.request();
if (status == PermissionStatus.granted) {
  print('Permission granted');
} else if (status == PermissionStatus.denied) {
  print('Denied. Show a dialog with a reason and again ask for the permission.');
} else if (status == PermissionStatus.permanentlyDenied) {
  print('Take the user to the settings page.');
}

完整代码:

class HomePage extends StatelessWidget {
  Future<void> _checkPermission() async {
    final serviceStatus = await Permission.locationWhenInUse.serviceStatus;
    final isGpsOn = serviceStatus == ServiceStatus.enabled;
    if (!isGpsOn) {
      print('Turn on location services before requesting permission.');
      return;
    }

    final status = await Permission.locationWhenInUse.request();
    if (status == PermissionStatus.granted) {
      print('Permission granted');
    } else if (status == PermissionStatus.denied) {
      print('Permission denied. Show a dialog and again ask for the permission');
    } else if (status == PermissionStatus.permanentlyDenied) {
      print('Take the user to the settings page.');
      await openAppSettings();
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: ElevatedButton(
          onPressed: _checkPermission,
          child: Text('Check Permission'),
        ),
      ),
    );
  }
}