Release APK In Flutter

• If you are a beginner in Flutter then you can check my blog Create a first app in Flutter. I have created app named as “flutter_release_apk”
• You can specify some app related setting in build.gradle under app folder (android/app/build.gradle). I have mentioned important settings below:
  
  
• applicationId
  This must be unique all around all apps in Google Play so wisely choose the name. Your app will be identified by this name and this can’t be changed.
  
  
• versionCode
  This is the app version code and needs to be updated each time you update the app on Google Play. Updating  with the same version of code will not be accepted in Google Play Store.
  

  For example purposes: 
  applicationId com.example.flutter_release_apk
  versionCode 1

• Now, we need to generate signing certificate to sign android apk. Following is the command to generate a signing certificate. You need to execute this command in the terminal and this will generate flutter_release_apk.jks file in the same folder where terminal opened.
  

  keytool -genkey -v -keystore flutter_release_apk.jks -alias alias_name -keyalg RSA -keysize 2048 -validity 10000

  Enter keystore password: abcd1234
  Re-enter new password: abcd1234

  What is your first and last name?
  [Unknown]: demo demo

  What is the name of your organizational unit?
  [Unknown]: demo

  What is the name of your organization?
  [Unknown]: demo

  What is the name of your City or Locality?
  [Unknown]: demo

  What is the name of your State or Province?
  [Unknown]: demo

  What is the two-letter country code for this unit?
  [Unknown]: 91

  Is CN=demo demo, OU=demo, O=demo, L=demo, ST=demo, C=91 correct?
  [no]: yes

  Generating 2,048 bit RSA key pair and self-signed certificate (SHA256withRSA) with a validity of 10,000 days
  for: CN=demo demo, OU=demo, O=demo, L=demo, ST=demo, C=91

  Enter key password for <alias_name>
  (RETURN if same as keystore password): abcd1234

  Re-enter new password: abcd1234
  [Storing flutter_release_apk.jks]

  So, now I have my flutter_release_apk.jksin directory where my terminal is open.

  NOTE
  Copy and Save this file safely because it is required every time you need to update your app. If you lose this file then there is no way to update your app in future

• Now, we need to create one file under android folder named as “key.properties”. This file stores the credentials for signing the release apk. Put the following code in this file and update as per your jsk file
  

  storePassword=abcd1234
  keyPassword=abcd1234
  keyAlias=alias_name
  storeFile=/Applications/AMPPS/www/Flutter_Demos/flutter_release_apk/flutter_release_apk.jks
  
  Save the file.

• Now, go back to build.gradle file under app directory (android/app/build.gradle). And now we need to define some settings for release apk generation. I have made bold some text that needs to be added or updated.
  

  1. def localProperties = new Properties()  
  2. def localPropertiesFile = rootProject.file('local.properties')  
  3. if (localPropertiesFile.exists()) {  
  4.     localPropertiesFile.withReader('UTF-8') {  
  5.         reader - > localProperties.load(reader)  
  6.     }  
  7. }  
  8. def flutterRoot = localProperties.getProperty('flutter.sdk')  
  9. if (flutterRoot == null) {  
  10.     throw new GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")  
  11. }  
  12. def flutterVersionCode = localProperties.getProperty('flutter.versionCode')  
  13. if (flutterVersionCode == null) {  
  14.     flutterVersionCode = '1'  
  15. }  
  16. def flutterVersionName = localProperties.getProperty('flutter.versionName')  
  17. if (flutterVersionName == null) {  
  18.     flutterVersionName = '1.0'  
  19. }  
  20. apply plugin: 'com.android.application'  
  21. apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"  
  22. def keystoreProperiesFile = rootProject.file("key.properties")  
  23. def keystoreProperies = new Properties()  
  24. keystoreProperies.load(new FileInputStream(keystoreProperiesFile))  
  25. android {  
  26.     compileSdkVersion 28  
  27.     lintOptions {  
  28.         disable 'InvalidPackage'  
  29.     }  
  30.     defaultConfig {  
  31.         applicationId "com.example.flutter_release_apk"  
  32.         minSdkVersion 16  
  33.         targetSdkVersion 28  
  34.         versionCode flutterVersionCode.toInteger()  
  35.         versionName flutterVersionName  
  36.         testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"  
  37.     }  
  38.     signingConfigs {  
  39.         release {  
  40.             keyAlias keystoreProperies["keyAlias"]  
  41.             keyPassword keystoreProperies["keyPassword"]  
  42.             storeFile file(keystoreProperies["storeFile"])  
  43.             storePassword keystoreProperies["storePassword"]  
  44.         }  
  45.     }  
  46.     buildTypes {  
  47.         release {  
  48.             // signingConfig signingConfigs.debug  
  49.             signingConfig signingConfigs.release  
  50.         }  
  51.     }  
  52. }  
  53. flutter {  
  54.     source '../..'  
  55. }  
  56. dependencies {  
  57.     testImplementation 'junit:junit:4.12'  
  58.     androidTestImplementation 'com.android.support.test:runner:1.0.2'  
  59.     androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'  
  60. }  

   

  Save the file.

• Now, Run the command flutter build apk --release in terminal. Following is my terminal log and you can see that my release apk is generated
  

  MyVss-Mac-mini:flutter_release_apk myvs $ flutter build apk --release
  Initializing gradle... 41.4s
  Resolving dependencies... 46.5s
  Calling mockable JAR artifact transform to create file: /Users/myvs/.gradle/caches/transforms-1/files-1.1/android.jar/fe6e28b8b8fb0fe581763b573c73df6a/android.jar with input /Users/myvs/Library/Android/sdk/platforms/android-28/android.jar
  Running Gradle task 'assembleRelease'...
  Running Gradle task 'assembleRelease'... Done 117.6s
  Built build/app/outputs/apk/release/app-release.apk (4.9MB).

• Now this generated apk can be uploaded on Google Play Store as release APK.

• Congratulations you can now upload as many apps as you need to upload on Google Play Store.

• Best of luck, I hope you will make awesome apps in the future :)))

Conclusion