flutter_snippets

=================================================================================================
  Install flutter
=================================================================================================
  1. Follow step 1 to 3 from below link
    https://flutter.dev/docs/get-started/install/macos
    
  2. Run command flutter in terminal it will download dart sdk
  
  3. Update the environment path.

    Open terminal.

    vim $HOME/.zshrc

    Press "I" key for going to insert mode.

    add the following line in the opened file:

    export PATH="$PATH:/YOUR_FLUTTER_DIR/flutter/bin"

    Press "Esc" then write :wq! in terminal and press enter to exit vim.

    Reopen the terminal and check "flutter doctor"
    
    if flutter doctor is showing any then its also shows command to solve that issue
    
    ***** alternative  way ***
    run this command in terminal to find available versions of jdk in your system
    /usr/libexec/java_home -V | grep jdk
    
    add jdk version in gradle.properties file
    org.gradle.java.home=/Users/ervinod/Library/Java/JavaVirtualMachines/corretto-1.8.0_302/Contents/Home


=================================================================================================
 git : Device not configured
=================================================================================================

In your project go to .git/config and add after username :password

before : https://username@bitbucket.org/repo.git

afetr : https://username:password@bitbucket.org/repo.git


=================================================================================================
  Set alignment of Widgets
=================================================================================================

Center vertically
Column(
  mainAxisAlignment: MainAxisAlignment.center,
  children: <Widget>[ ... ],
)
Center horizontally
Column(
  crossAxisAlignment: CrossAxisAlignment.center,
  children: <Widget>[ ... ],
)
But if the column is hugging its content then just wrap it in a Center widget

Center(
  child: Column(
    children: <Widget>[ ... ],
  ),
)

=================================================================================================
  Change Flutter App Name
=================================================================================================

Android
Open AndroidManifest.xml (located at android/app/src/main)

<application
    android:label="App Name" ...> // Your app name here
iOS
Open info.plist (located at ios/Runner)

<key>CFBundleName</key>
<string>App Name</string> // Your app name here

Don't forget to run
flutter clean


=================================================================================================
  Add delay
=================================================================================================

new Future.delayed(const Duration(seconds: 1)); //recommend

new Timer(const Duration(seconds: 1), ()=>print("1 second later."));

sleep(const Duration(seconds: 1)); //import 'dart:io';

new Stream.periodic(const Duration(seconds: 1), (_) => print("1 second later.")).first.then((_)=>print("Also 1 second later."));

=================================================================================================
  Show AlertDialog
=================================================================================================
  
    void _showSignoutDialog(BuildContext context, GlobalKey<ScaffoldState> formKey, SharedPreferences sharedPreferences){
    showDialog(
      context: context,
      builder: (BuildContext context) {
        return AlertDialog(
          title: new Text(TextFile.SIGNOUT_TITLE, style: TextStyle(color: Colors.black.withOpacity(0.8))),
          content: new Text(TextFile.SIGNOUT_DESCRIPTION),
          actions: <Widget>[
            new FlatButton(
              child: new Text(TextFile.BUTTON_CANCEL),
              onPressed: () async {
                    Navigator.of(context).pop();
              },
            ),
            new FlatButton(
              child: new Text(TextFile.BUTTON_SIGNOUT),
              onPressed: () {
                    Navigator.of(context).pop();
              },
            ),
          ],
        );
      },
    );
  }


=================================================================================================
  Change button color if text entered in textfield is valid
=================================================================================================
  
  https://stackoverflow.com/a/58691020
  
  
 show hide widget on UI using Bloc
 https://stackoverflow.com/a/55594815


=================================================================================================
  Change button color if text entered in textfield is valid
=================================================================================================

1. In your pubspec.yaml file add this:

dependencies:
  device_info: ^0.4.0+4

2. Create a method:

Future<String> _getId() async {
  DeviceInfoPlugin deviceInfo = DeviceInfoPlugin();
  if (Theme.of(context).platform == TargetPlatform.iOS) {
    IosDeviceInfo iosDeviceInfo = await deviceInfo.iosInfo;
    return iosDeviceInfo.identifierForVendor; // unique ID on iOS
  } else {
    AndroidDeviceInfo androidDeviceInfo = await deviceInfo.androidInfo;
    return androidDeviceInfo.androidId; // unique ID on Android
  }
}

3. Use it like:

String deviceId = await _getId();

//or u can call below function to get more device info

static Future<List<String>> getDeviceDetails() async {
    String deviceName;
    String deviceVersion;
    String identifier;
    final DeviceInfoPlugin deviceInfoPlugin = new DeviceInfoPlugin();
    try {
      if (Platform.isAndroid) {
        var build = await deviceInfoPlugin.androidInfo;
        deviceName = build.model;
        deviceVersion = build.version.toString();
        identifier = build.androidId;  //UUID for Android
      } else if (Platform.isIOS) {
        var data = await deviceInfoPlugin.iosInfo;
        deviceName = data.name;
        deviceVersion = data.systemVersion;
        identifier = data.identifierForVendor;  //UUID for iOS
      }
    } on PlatformException {
      print('Failed to get platform version');
    }

//if (!mounted) return;
return [deviceName, deviceVersion, identifier];
}

=================================================================================================
  Make specific parts of a text clickable (spannable/ rich text)
=================================================================================================

Widget build(BuildContext context) {
    TextStyle defaultStyle = TextStyle(color: Colors.grey, fontSize: 20.0);
    TextStyle linkStyle = TextStyle(color: Colors.blue);
    return RichText(
      text: TextSpan(
        style: defaultStyle,
        children: <TextSpan>[
          TextSpan(text: 'By clicking Sign Up, you agree to our '),
          TextSpan(
              text: 'Terms of Service',
              style: linkStyle,
              recognizer: TapGestureRecognizer()
                ..onTap = () {
                  print('Terms of Service"');
                }),
          TextSpan(text: ' and that you have read our '),
          TextSpan(
              text: 'Privacy Policy',
              style: linkStyle,
              recognizer: TapGestureRecognizer()
                ..onTap = () {
                  print('Privacy Policy"');
                }),
        ],
      ),
    );
  }
  
=================================================================================================
  Password TextField toggle
=================================================================================================
  1. Declase boolean variable to keep track of visibility
  bool _obscurePassword = true;
  
  2. Write function to toggle boolean variable
  void _togglePasswordVisibility() {
    setState(() {
      _obscurePassword = !_obscurePassword;
    });
  }
  
  3. Configure TextFormField widget
  
  TextFormField(
      obscureText: _obscurePassword,
      decoration: InputDecoration(
        hintText: "Enter your password",
          suffixIcon: IconButton(
            onPressed: () => _togglePasswordVisibility(),
            icon: Icon(Icons.remove_red_eye,  color: this._obscurePassword ? Colors.blue : Colors.grey,),
          ),
      ),
    )
    
=================================================================================================
  build production/release apk for flutter project
=================================================================================================

  1. create key.properties file and modify build.gradle file according to below link
    https://flutter.dev/docs/deployment/android
  2. use below command to build release apk
    flutter build apk --release
    
=================================================================================================
  call post api as raw request body
=================================================================================================    
    
    
    Map data = {
      'mobile_no': mobile_no,
      'otp': enteredOTP,
    };

    //encode Map to JSON
    var requestBody = json.encode(data);

    debugPrint(requestBody);

 
      if(response.statusCode==200){
        // api success 
        Map<String , dynamic> jsonResopnse = json.decode(response.body);
        http.Response response = await http.post(ApiConstants.VERIFYOTP, body: requestBody);
       
      }else {
        // api error
      }
      
=================================================================================================
  Manage sqlite db version in flutter
=================================================================================================    
      
      Future<Database> initDb() async {

        final databasesPath = await getDatabasesPath();
        final path = join(databasesPath, "database.db");

        var db = await openDatabase(path);

        //if database does not exist yet it will return version 0
        if (await db.getVersion() < NEW_DB_VERSION) {

          db.close();

          //delete the old database so you can copy the new one
          await deleteDatabase(path);

          try {
            await Directory(dirname(path)).create(recursive: true);
          } catch (_) {}

          //copy db from assets to database folder
          ByteData data = await rootBundle.load("assets/databases/database.db");
          List<int> bytes = data.buffer.asUint8List(data.offsetInBytes, data.lengthInBytes);
          await File(path).writeAsBytes(bytes, flush: true);

          //open the newly created db 
          db = await openDatabase(path);

          //set the new version to the copied db so you do not need to do it manually on your bundled database.db
          db.setVersion(NEW_DB_VERSION);

        }

        return db;
      }
    }

=================================================================================================
  Get today's formated date
=================================================================================================    
  import 'package:intl/intl.dart';
  
  DateTime now = new DateTime.now();
    DateTime date = new DateTime(now.year, now.month, now.day);

    final customDateFormat = new DateFormat('yyyy-MM-dd');
    var mDate = customDateFormat.format(date);
   
   
   String getFormattedDate(String dateString){
    try{
      DateTime now = DateTime.parse(dateString);
      //String mDate = DateFormat().addPattern("yyyy-MM-dd HH:mm:ss").format(now);
      String mDate = DateFormat().addPattern("dd-MM-yyyy").format(now);
      //final customDateFormat = new DateFormat('dd-MM-yyyy');
      //var mDate = customDateFormat.format(now);
      return mDate.toString();
    }catch(_){
        return dateString;
    }
  }
   
=================================================================================================
  Parse JSON Object
=================================================================================================    
  
  List<dynamic> _declarationList = [];


  var userDetails = _declarationList[index]["user_details"];
  var user_name = userDetails["name"];
  
  var userDetails = json.decode(_declarationList[index]["user_details"]);
  var user_name = userDetails["name"];
  
  Map<String, dynamic> userDetails = json.decode(optionArray);
  var user_name = userDetails["name"];

=================================================================================================
  Add press back agait to exit app message
=================================================================================================  

  //add dependency to show toast message
  fluttertoast: 4.0.1

  DateTime currentBackPressTime;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      ...
      body: WillPopScope(child: getBody(), onWillPop: onWillPop),
    );
  }
  
  Future<bool> onWillPop() {
    DateTime now = DateTime.now();
    if (currentBackPressTime == null ||
        now.difference(currentBackPressTime) > Duration(seconds: 2)) {
      currentBackPressTime = now;
      Fluttertoast.showToast(msg: "Press BACK again to exit...");
      return Future.value(false);
    }
    return Future.value(true);
  }
  
  
=================================================================================================
  Show timer inside dialog (alert dialog)
================================================================================================= 

  1. Add code in intiState()
  @override
  void initState() {
    super.initState();
    super.init(context, _scaffoldState, state: this);
    _events = new StreamController<int>.broadcast();
    _events.add(5);// 5 second timer
  }
  
  2. create timer
  Timer _timer;
  StreamController<int> _events;//state level declaration
  
  void _startTimer() {
    _counter = 5;
    if (_timer != null) {
      _timer.cancel();
    }
    _timer = Timer.periodic(Duration(seconds: 1), (timer) {
      //setState(() {
      (_counter > 0) ? _counter-- : _timer.cancel();
      //});
      print(_counter);
      _events.add(_counter);
    });
  }

  
  3. declare function to show AlertDialog
  
  void showAlertDialog(BuildContext ctx) {
    var alert = AlertDialog(
      // title: Center(child:Text('Enter Code')),
        shape: RoundedRectangleBorder(
            borderRadius: BorderRadius.all(Radius.circular(20.0))),
        backgroundColor: Colors.grey[100],
        elevation: 0.0,
        content: StreamBuilder<int>(
            stream: _events.stream,
            builder: (BuildContext context, AsyncSnapshot<int> snapshot) {
              bool isVisible = false;
              if(snapshot.data!=null && snapshot.data.toString()=="0"){
                isVisible = true;
              }
              print(snapshot.data.toString());
               return Container(
                height: 215,
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.center,
                  children: <Widget>[
                    Padding(
                        padding: const EdgeInsets.only(
                            top: 10, left: 10, right: 10, bottom: 15),
                        child: Text(
                          'Enter Code',
                          style: TextStyle(
                              color: Colors.green[800],
                              fontWeight: FontWeight.bold,
                              fontSize: 16),
                        )),
                    Container(
                      height: 70,
                      width: 180,
                      child: TextFormField(
                        style: TextStyle(
                            fontSize: 20, fontWeight: FontWeight.bold),
                        textAlign: TextAlign.center,
                        decoration: InputDecoration(
                          enabledBorder: OutlineInputBorder(
                              borderSide:
                              BorderSide(color: Colors.green, width: 0.0)),
                        ),
                        keyboardType: TextInputType.number,
                        maxLength: 10,
                      ),
                    ),
                    SizedBox(
                      height: 1,
                    ),
                    Text(snapshot.hasData?'00:${snapshot.data.toString()}':'00:00'),
                    SizedBox(
                      height: 15,
                    ),
                    Row(
                      mainAxisAlignment: MainAxisAlignment.spaceBetween,
                      children: <Widget>[
                        ClipRRect(
                          borderRadius: BorderRadius.circular(25),
                          child: Material(
                            child: InkWell(
                              onTap: () {
                                //Navigator.of(ctx).pushNamed(SignUpScreenSecond.routeName);
                              },
                              child: Container(
                                width: 100,
                                height: 50,
                                decoration: BoxDecoration(
                                  borderRadius: BorderRadius.circular(25),
                                  gradient: LinearGradient(
                                      colors: [
                                        Colors.green,
                                        Colors.grey,
                                      ],
                                      begin: Alignment.topLeft,
                                      end: Alignment.bottomRight),
                                ),
                                child: Center(
                                    child: Text(
                                      'Validate',
                                      style: TextStyle(
                                          color: Colors.white,
                                          fontSize: 16,
                                          fontWeight: FontWeight.bold),
                                    )),
                              ),
                            ),
                          ),
                        ),
                        Visibility(
                          visible: isVisible,
                          child: ClipRRect(
                            borderRadius: BorderRadius.circular(25),
                            child: Material(
                              child: InkWell(
                                onTap: () {},
                                child: Container(
                                  width: 100,
                                  height: 50,
                                  decoration: BoxDecoration(
                                    borderRadius: BorderRadius.circular(25),
                                    gradient: LinearGradient(
                                        colors: [
                                          Colors.grey,
                                          Colors.green,
                                        ],
                                        begin: Alignment.topLeft,
                                        end: Alignment.bottomRight),
                                  ),
                                  child: Center(
                                      child: Text(
                                        'Resend',
                                        style: TextStyle(
                                            color: Colors.white,
                                            fontSize: 16,
                                            fontWeight: FontWeight.bold),
                                      )),
                                ),
                              ),
                            ),
                          ),
                        )
                      ],
                    ), //new column child
                  ],
                ),
              );
            }));
    showDialog(
        context: ctx,
        builder: (BuildContext c) {
          return alert;
        });
  }
  
  4. show AlertDialog
  _startTimer();//to start timer
  showAlert(context);//to show dialog


=================================================================================================
  Lock Screen Rotation of entire app
=================================================================================================

  1. Create following mixin PortraitModeMixin.dart file
  
  import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

/// Forces portrait-only mode application-wide
/// Use this Mixin on the main app widget i.e. app.dart
/// Flutter's 'App' has to extend Stateless widget.
///
/// Call `super.build(context)` in the main build() method
/// to enable portrait only mode
mixin PortraitModeMixin on StatelessWidget {
  @override
  Widget build(BuildContext context) {
    _portraitModeOnly();
    return null;
  }
}

/// Forces portrait-only mode on a specific screen
/// Use this Mixin in the specific screen you want to
/// block to portrait only mode.
///
/// Call `super.build(context)` in the State's build() method
/// and `super.dispose();` in the State's dispose() method
mixin PortraitStatefulModeMixin<T extends StatefulWidget> on State<T> {
  @override
  Widget build(BuildContext context) {
    _portraitModeOnly();
    return null;
  }

  @override
  void dispose() {
    _enableRotation();
  }
}

/// blocks rotation; sets orientation to: portrait
void _portraitModeOnly() {
  SystemChrome.setPreferredOrientations([
    DeviceOrientation.portraitUp,
    DeviceOrientation.portraitDown,
  ]);
}

void _enableRotation() {
  SystemChrome.setPreferredOrientations([
    DeviceOrientation.portraitUp,
    DeviceOrientation.portraitDown,
    DeviceOrientation.landscapeLeft,
    DeviceOrientation.landscapeRight,
  ]);
}

2. Use this mixin in main.dart file

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

class MyApp extends StatelessWidget with PortraitModeMixin{
  @override
  Widget build(BuildContext context) {
    super.build(context);//important
    return MaterialApp(
      title: "Demo App",
      debugShowCheckedModeBanner: false,
      initialRoute: SplashScreen.routeName,
      routes: routes,
    );
  }
}
  
  To block rotation in a specific screen implement PortraitStatefulModeMixin<SampleScreen> in 
  the specific screen's state. Remember to call super.build(context) in the State's build() method 
  and super.dispose() in dispose() method. If your screen is a StatelessWidget - simply repeat the 
  App's solution (previous example) i.e. use PortraitModeMixin.
  
  /// Specific screen
class SampleScreen extends StatefulWidget {
  SampleScreen() : super();

  @override
  State<StatefulWidget> createState() => _SampleScreenState();
}

class _SampleScreenState extends State<SampleScreen>
    with PortraitStatefulModeMixin<SampleScreen> {
  @override
  Widget build(BuildContext context) {
    super.build(context);
    return Text("Flutter - Block screen rotation example");
  }

  @override
  void dispose() {
     super.dispose();
  }
}
  
  
=================================================================================================
 Configure ImagePicker plugin for iOS build
=================================================================================================

  add below lines in end of info.plist file (i.e. just above tag </dict>)
  //file location - <project root>/ios/Runner/Info.plist

  <key>NSPhotoLibraryUsageDescription</key>
  <string>Need to upload image</string>
  <key>NSCameraUsageDescription</key>
  <string>Need to upload image</string>
  <key>NSMicrophoneUsageDescription</key>
  <string>Need to upload image</string>
  
=================================================================================================
 NDK version issue solution
=================================================================================================

  Error: No version of NDK matched the requested version 20.0.5594570. Versions available locally: 21.0.6113669
  
  Step 1. Upgrade gradle plugin version - android -> build.gradle
          classpath 'com.android.tools.build:gradle:4.1.2'
  Step 2. Change gradle distribution url - android->gradle->wrapper->gradle-wrapper.properties
          distributionUrl=https\://services.gradle.org/distributions/gradle-6.5-all.zip
  Step 3. Remove NDK path from local.properties
  Step 4. Clean , pub get and run
  
  or you can explictly set ndk version in build.gradle
      android {
        compileSdkVersion 29
        ndkVersion "21.0.6113669"
  
=================================================================================================
 Trim String
=================================================================================================
  
  String link = 'http://sales.local/api/v1/payments/454/ticket/verify?token=jhvycygvjhbknm.eyJpc3MiOiJodH';
  String delimiter = '/ticket';
  int lastIndex = link.indexOf(delimiter);
  String trimmed = link.substring(0,lastIndex);
  print(trimmed);


=================================================================================================
 Get remaining time by comparing 2 dates
=================================================================================================

String _getRemainingTime(Duration duration) {
  //if you want like 02 hours instead of 2 hours
  //String twoDigits(int n) => n.toString().padLeft(2, "0");
  /*String twoDigits(int n) => n.toString();
  String twoDigitDays = twoDigits(duration.inDays.remainder(7));
  String twoDigitHours = twoDigits(duration.inHours.remainder(24));
  String twoDigitMinutes = twoDigits(duration.inMinutes.remainder(60));
  String twoDigitSeconds = twoDigits(duration.inSeconds.remainder(60));*/


  int twoDigits(int n) => n;
  int daysRemain = twoDigits(duration.inDays.remainder(7));
  int hoursRemain = twoDigits(duration.inHours.remainder(24));
  int minutesRemain = twoDigits(duration.inMinutes.remainder(60));
  int secondsRemain = twoDigits(duration.inSeconds.remainder(60));

  if(daysRemain==0){
    return "$hoursRemain Hours left";
  }
  if(daysRemain>0){
    return "$daysRemain Days $hoursRemain hours left";
  }

  if(daysRemain==0 && hoursRemain==0 ){
    return 'Less than a hour left';
  }
  return "$daysRemain Days $hoursRemain hours left";
}


=================================================================================================
 Get ago time by comparing 2 dates
=================================================================================================

  static String timeAgo(DateTime date, {bool numericDates = true}) {
    if (date == null) return "";

    final date2 = DateTime.now();
    final difference = date2.difference(date);
//    print('day dff : ${difference.inDays}');

    if (difference.inSeconds < 2) {
      return 'Just now';
    } else if (difference.inSeconds <= 59) {
      return '${difference.inSeconds} Sec ago';
    } else if (difference.inMinutes <= 1) {
      return numericDates ? '1 Min ago' : 'A min ago';
    } else if (difference.inMinutes <= 59) {
      return '${difference.inMinutes} Min ago';
    } else if (difference.inHours == 1) {
      return numericDates ? '1 Hr ago' : 'An Hr ago';
    } else if (difference.inHours <= 24) {
      return '${difference.inHours}h ago';
    } else if (difference.inDays <= 1) {
      return numericDates ? '1d ago' : 'Yesterday';
    } else if (difference.inDays <= 6) {
      return '${difference.inDays}d ago';
    } else if ((difference.inDays / 7).floor() <= 1) {
      return numericDates ? '1 week ago' : 'Last week';
    } else if ((difference.inDays / 7).floor() <= 4) {
      return '${(difference.inDays / 7).floor()} weeks ago';
    } else if ((difference.inDays / 30).floor() <= 1) {
      return numericDates ? '1 month ago' : 'Last month';
    } else if ((difference.inDays / 30).floor() <= 11) {
      return '${(difference.inDays / 30).floor()} months ago';
    } else if ((difference.inDays / 365).floor() <= 1) {
      return numericDates ? '1 yr ago' : 'Last year';
    } else {
      return '${(difference.inDays / 365).floor()} years ago';
    }
  }


=================================================================================================
 Get .apk from .aab file
=================================================================================================
If you want to install apk from your aab to your device for testing purpose then you need to edit 
the configuration(app is default) before running it on the connected device.
or

For Debug apk command,

bundletool build-apks --bundle=/MyApp/my_app.aab --output=/MyApp/my_app.apks
For Release apk command,

bundletool build-apks --bundle=/MyApp/my_app.aab --output=/MyApp/my_app.apks
--ks=/MyApp/keystore.jks
--ks-pass=file:/MyApp/keystore.pwd
--ks-key-alias=MyKeyAlias
--key-pass=file:/MyApp/key.pwd

=================================================================================================
 show loader
=================================================================================================

  void showLoader() {
    showDialog(
      context: context,
      barrierDismissible: false,///dismiss on touch outside loader
      builder: (BuildContext context) {
        return WillPopScope(
          onWillPop: () async => false,///to dismiss loader on backbutton key press
          child: Center(
            child: SizedBox(
              width: 30,
              height: 30,
              child: CircularProgressIndicator(
              ),
            ),
          ),
        );
      },
    );
  }

=================================================================================================
 get comma seperated string from List<String>
=================================================================================================

List cities = ['NY', 'LA', 'Tokyo'];
String formattedString = getCommaSeparatedString(cities);
print(formattedString);

String getCommaSeparatedString(List list) {
  String formattedStr ='';
  for(var i in list) {
    formattedStr += '$i, ';
  }
  return formattedStr.replaceRange(formattedStr.length -2, formattedStr.length, '');
}

String getCommaSeparatedString(List<String> arguments) {
  String str = cities.join(', ');
  return str;
}


=================================================================================================
 Detect left/right swipe on page/widget
=================================================================================================
1. wrap widget with GestureDetector
2. detect swipe in onPanUpdate method


                GestureDetector(
                    onPanUpdate: (details) {
                      // Swiping in right direction.
                      if (details.delta.dx > 0) {
                        EasyDebounce.debounce(
                          "swipe_backward_debounce",
                          const Duration(milliseconds: 200),
                          () {
                            log("swipe to right, go back");
                          },
                        );
                      } else if (details.delta.dx < 0) {
                        EasyDebounce.debounce(
                          "swipe_forward_debounce",
                          const Duration(milliseconds: 200),
                          () {
                            log("swipe to left, go forward");
                          },
                        );
                      }
                    },
                    child: Container(),
                  )


=================================================================================================
 Generate SHA key for flutter project
=================================================================================================

 *** GUI method ***

  1. Open Project in Android Studio in PROJECT view
  2. Reveal android folder
  3. Right click "gradlew" file and select Open in Terminal
  4. Go to the terminal view and paste: ./gradlew signingReport gradlew signingReport if you're using Unix-based system like Mac or a PowerShell.
  5. Press enter and scroll to "Variant: release" to get the SHA1 key


`*** Terminal method ***

  Go to the project folder in the terminal.

  Mac keytool -list -v -keystore ./android/debug.keystore -alias androiddebugkey -storepass android -keypass android
  Windows keytool -list -v -keystore "\.android\debug.keystore" -alias androiddebugkey -storepass android -keypass android
  Linux keytool -list -v -keystore ~/.android/debug.keystore -alias androiddebugkey -storepass android -keypass android


=================================================================================================
 Create keystore for Android build
=================================================================================================

1. Create Keystore

To create Keystore run this command

move to your directoty - yourapp/android and run below command

keytool -genkey -v -keystore keystore.jks -storepass Android@123 -alias android -keypass Android@123 -keyalg RSA -keysize 2048 -validity 10000

Then fill the required details asked in commandline

Enter keystore password: javacaps
What is your first and last name?
[Unknown]: development.sun.com
What is the name of your organizational unit?
[Unknown]: Development
what is the name of your organization?
[Unknown]: Sun
What is the name of your City or Locality?
[Unknown]: Monrovia
What is the name of your State or Province?
[Unknown]: California
What is the two-letter country code for this unit?
[Unknown]: US
Is<CN=development.sun.com, OU=Development, O=Sun, L=Monrovia, ST=California, 
C=US> correct?
[no]: yes

Enter key password for <client>
    (RETURN if same as keystore password):

2. Create key.properties file in android directory and add below content to it

storePassword=MyApp@2024
keyPassword=MyApp@2024
keyAlias=myapp
storeFile=../keystore.jks

3. use keys created in step 2 to generate release build
open app/build.gradle file and add release config

//=============== Keystore Config ===============
def keystoreProperties = new Properties()
def keystorePropertiesFile = rootProject.file('key.properties')
if (keystorePropertiesFile.exists()) {
    keystoreProperties.load(new FileInputStream(keystorePropertiesFile))
}
//===============               ===============
// this code should ideally be added above appy plugin section
// apply plugin: 'com.android.application'

Add below code below defaultConfig{} section

    signingConfigs {
        release {
            keyAlias keystoreProperties['keyAlias']
            keyPassword keystoreProperties['keyPassword']
            storeFile keystoreProperties['storeFile'] ? file(keystoreProperties['storeFile']) : null
            storePassword keystoreProperties['storePassword']
        }
    }

    buildTypes {
        release {
            signingConfig signingConfigs.release
            minifyEnabled true
            shrinkResources true
        }

        debug{
            signingConfig signingConfigs.debug
        }
    }


=================================================================================================
 Create app build (while using app flavors)
=================================================================================================

set appropriate version code in pubspec.yaml (ex 1.0.0+1)

Command to run App
flutter run --flavor PROD -t lib/main_prod.dart 

Commant to build APK
flutter build apk --release --flavor PROD -t lib/main_prod.dart 

Commant to build App Bundle
flutter build appbundle --release --flavor PROD -t lib/main_prod.dart


=================================================================================================
  Date Manipulation
=================================================================================================

FIRST DAY OF THE WEEK
DateTime findFirstDateOfTheWeek(DateTime dateTime) {
    return dateTime.subtract(Duration(days: dateTime.weekday - 1));
}

LAST DAY OF THE WEEK
DateTime findLastDateOfTheWeek(DateTime dateTime) {
    return dateTime
        .add(Duration(days: DateTime.daysPerWeek - dateTime.weekday));
}

LAST DAY OF THE MONTH
DateTime findLastDateOfTheMonth(DateTime dateTime) {
    return DateTime(dateTime.year, dateTime.month + 1, 0);
}

FIRST DAY OF THE MONTH
DateTime findFirstDateOfTheMonth(DateTime dateTime) {
    return DateTime(dateTime.year, dateTime.month, 1);
}

LAST DAY OF THE YEAR
DateTime findLastDateOfTheYear(DateTime dateTime) {
    return DateTime(dateTime.year, 12, 31);
}

FIRST DAY OF THE YEAR
DateTime findFirstDateOfTheYear(DateTime dateTime) {
    return DateTime(dateTime.year, 1, 1); }


=================================================================================================
  Working with FLAVORS
=================================================================================================

Command to run App
flutter run --flavor PROD -t lib/main_prod.dart 

Commant to build APK
flutter build apk --release --flavor PROD -t lib/main_prod.dart 

Commant to build App Bundle
flutter build appbundle --release --flavor PROD -t lib/main_prod.dart


=================================================================================================
  IOS build related queries and answers
=================================================================================================

**** Upload ios build when another build is already in review ***

Go to Distribution tab
From left side menu, Go to General=> App Review
cancele submission for the build which is in review


Now got to Distribution tab 
Now in iOS section(top left) build should show int red with Rejected by Developer text
Now in Build section remove old build(for which we cancelled the submission) and 
selectt new build click SAVE and the Submit for Review


*** Adding build on TestFlight for first time ***
From XCode upload build to TestFlight
Go to TestFlight tab
Now create group for External Testing to invite users using email
click Create group or PLUS button from left side menus
Fill required details and select build to submit for testing
Now click Create Public Link button on "Testers" Tab
It will ask to fill some details
select Open To Anyone and if required add tester limit
then SUBMIT

Now it should show some link like
https://testflight.apple.com/join/JYR4xXXx
using this link you can invite testers to test your app

Note that testers cannot join public link until the group has an approved build.
to get build approved it usuallay takes 8-10 hours


*** Updating IOS build ***

while updating ios build you need to follow different versioning as compared to Android

suppose the last APPROVED build version is 1.0.0+1
Now you need to make some minor chnage and want to upload new build again
this time yon cant use version like 1.0.0+2 (means just incremented the build number)
It is must to change minor version number like 1.1.11+1

Note that if version is not live 1.0.0+1 and u want to update the build
then u junst need to increment the build number, but this is applicable
only when last updated version if not live(means it is only available on TestFlight)