Generating Signed APK with React Native

How I am going to build an APK with React Native? 

Step -1

•  Seth the path of Java

Step -2

• we can generate a private signing key using keytool.
• open our Command Prompt (terminal) and copy and paste the below command.

keytool -genkey -v -keystore my-release-key.keystore -alias my-key-alias -keyalg RSA -keysize 2048 -validity 10000

or

keytool -genkey -v -keystore mykeystore.keystore -alias mykeyalias -keyalg RSA -keysize 2048 -validity 10000

or


Generating a signing key #
You can generate a private signing key using keytool.

keytool -genkey -v -keystore my-release-key.keystore -alias my-key-alias -keyalg RSA -keysize 2048 -validity 10000

This command prompts
you for passwords for the keystore and key, and to provide the Distinguished Name fields for your key. It then generates the keystore as a file called my-release-key.keystore.

The keystore contains a single key, valid for 10000 days. The alias is a name that you will use later when signing your app, so remember to take note of the alias.

Note: Remember to keep your keystore file private and never commit it to version control.

Step -3 

• Note    Remember Entered password of my-key-alias 
• I recommended to Enter  password as:- android
• default keystore file location is our under user directory like in mycase

Step -4

• Adding Keystore to our project

Now, we have to place the created keystore file under the android/app directory in your react native project folder.

In My case

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Step -5

Add the following lines to android\app\build.gradle

signingConfigs {

release {

if (project.hasProperty('MYAPP_RELEASE_STORE_FILE')) {

storeFile file(MYAPP_RELEASE_STORE_FILE)

storePassword MYAPP_RELEASE_STORE_PASSWORD

keyAlias MYAPP_RELEASE_KEY_ALIAS

keyPassword MYAPP_RELEASE_KEY_PASSWORD

}

}

signingConfig signingConfigs.release

Like this

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Step -6
Add the following lines to gradle.properties
or
android/gradle.properties

Copy the code paste it

MYAPP_RELEASE_STORE_FILE=my-release-key.keystore
MYAPP_RELEASE_KEY_ALIAS=my-key-alias
MYAPP_RELEASE_STORE_PASSWORD=android
MYAPP_RELEASE_KEY_PASSWORD=android

Note: my-release-key.keystore should be same name

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Step -7

Generating APK 

Place your terminal directory to android using,

cd android

Then run the following command

For windows --> gradlew assembleRelease

            OR shorthand

cd android & gradlew assembleRelease

under below directory available our apk

C:\Users\sapan\Desktop\React Native\demo\android\app\build\outputs\apk\release
name:-
app-release.apk

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Common Errors:-

Google play says: “You need to use a different package name” - why?

Regardless of the name of the .apk file, the package name of the Application contents inside it must be unique.

Apart from correcting app name in the AndroidManifest.xml ,
I also had to change applicationId in the android/app/gradle.build file.

 defaultConfig {
    applicationId "com.example.changednameofmyapp"
 
}

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Building a Debug APK for React Native apps


What is Debug Apk:

• An Android app will execute in debug mode in the development environment
• The debug apk must be enabled the debug logging, StrictMode and the debugging options.
• The debug apk not ready for the app stores.

Creating the debug Apk 
Open a terminal/command prompt inside the root directory of your project and run the following commands:
1 - mkdir  android\app\src\main\assets

2 - react-native bundle --platform android --dev false --entry-file index.js --bundle-output android/app/src/main/assets/index.android.bundle --assets-dest android/app/src/main/res

3 -  Change to /android directory and run gradlew to build the APK:

gradlew clean assembleDebug

   or

cd android && gradlew clean assembleDebug

4 - app-debug.apk
C:\Users\sapan\Desktop\React Native\helloworld\android\app\build\outputs\apk\debug
app-debug.apk

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Reducing the size of the APK
You need to enable Proguard which removes the bytecode and dependencies which your app doesn’t use and reducing the size of your APK slightly.

Add the following line under buildTypes in android\app\build.gradle
android {
    ...
    buildTypes {
        release {
            ...
            minifyEnabled true
    }
 
}

reduce file size

changing the following line in android/app/build.gradle:
by default it's false
def enableSeparateBuildPerCPUArchitecture = true

def enableSeparateBuildPerCPUArchitecture = true

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Some Tips 
Using command prompt or Terminal 
Then open the terminal on your computer and type:

Debug
keytool -list -alias androiddebugkey -keystore android\app\debug.keystore

if you want to print  all output
use -v flag
keytool -list -v -alias androiddebugkey -keystore android\app\debug.keystore 


Release
keytool -list -alias my-key-alias -keystore android\app\my-release-key.keystore
or
keytool -list -alias my-key-alias -keystore android\app\my-release-key.keystore
Note alias is 
my-key-alias

where i get alias as follow below command, that is used for generate Keystore file
keytool -genkey -v -keystore my-release-key.keystore -alias my-key-alias -keyalg RSA -keysize 2048 -validity 10000

This is name of keystore like my-release-key
you can put any name , that is not matter

One more example
here alias is mykeyalias

keytool -list -alias mykeyalias -keystore android\app\my-release-key.keystore

keytool -genkey -v -keystore mykeystore.keystore -alias mykeyalias -keyalg RSA -keysize 2048 -validity 10000

keyhash
Debug 
keytool -exportcert -alias androiddebugkey -keystore android/app/debug.keystore | openssl sha1 -binary | openssl base64

out put ;Xo8WBi6jzSxKDVR4drqm84yr9iU=

Release

keytool -exportcert -alias my-key-alias -keystore android/app/my-release-key.keystore | openssl sha1 -binary | openssl base64

or outside project directory

keytool -exportcert -alias my-key-alias -keystore "C:\Users\sapan\Desktop\React Native\reduxpro\android\app\my-release-key.keystore" | openssl sha1 -binary | openssl base64