Hi Everyone,

Every time when you finish your development and try to build the app bundle, always face some errors. For that, I have come up with this idea to show you how quickly we can men this barrier. Let's see the steps:

First Step: Adding a launcher icon

You can easily do this by following the package Flutter_launcher_icon. It is necessary to publish your app. Otherwise you may get rejection message.

Second Step: Signing the app

To sign the app, we need to upload a key store, which represents the secret key for signing the app.  There are two steps. One is Android Studio Key Generation App, and the other is running a code on your PC. As I am a windows user, I will show you the windows process, Linux/MAC user's process is almost similar. You need to have JAVA installed on your PC. As my Java folder is created in your drive, mine is in C drive, go to the jre/bin dir, and I need to paste the following code in the command prompt:

C:/Program Files (x86)/Java/jre1.8.0_351/bin/cmd.exe

keytool -genkey -v -keystore D:\upload-keystore.jks -storetype JKS -keyalg RSA -keysize 2048 -validity 10000 -alias upload

The keystone file will create in the C: drive. You can choose your own location. 

Third Step: Reference the Keystore from the app

Create a file named [project]/android/key.properties,  this file contains the keystone reference

Paste the below code in key.properties

storePassword=[your password]
keyPassword=[your password]
keyAlias=upload
storeFile=D:/upload-keystore.jks

Forth Step: Configure signing in gradle

Configure gradle to use your upload key when building your app in release mode by editing the below directory file.

[project]/android/app/build.gradle file. 

Add the keystore information from your properties file before the android block:

 def keystoreProperties = new Properties()
   def keystorePropertiesFile = rootProject.file('key.properties')
   if (keystorePropertiesFile.exists()) {
       keystoreProperties.load(new FileInputStream(keystorePropertiesFile))
   }

   android {
         ...
   }

Load the key.properties file into the keystoreProperties object. Find the buildTypes block:

 buildTypes {
       release {
           // TODO: Add your own signing config for the release build.
           // Signing with the debug keys for now,
           // so `flutter run --release` works.
           signingConfig signingConfigs.debug
       }
   }

And replace it with the following signing configuration info:

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

That's it. Now run the below command to build the app bundle for the Google play store. 

flutter build apk 

or 

flutter build appbundle

Hope this might help in your development journey.

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