blog_cryptoobject_create_biometricprompt

class MainActivity : AppCompatActivity() {
  ...
   private lateinit var biometricPrompt: BiometricPrompt
   ...

   override fun onCreate(savedInstanceState: Bundle?) {
       super.onCreate(savedInstanceState)
       setContentView(R.layout.activity_main)
       ...
       biometricPrompt = createBiometricPrompt()
       ...
   }

   private fun createBiometricPrompt(): BiometricPrompt {
       val executor = ContextCompat.getMainExecutor(this)

       val callback = object : BiometricPrompt.AuthenticationCallback() {
           override fun onAuthenticationError(errorCode: Int, errString: CharSequence) {
               super.onAuthenticationError(errorCode, errString)
               Log.d(TAG, "$errorCode :: $errString")
           }

           override fun onAuthenticationFailed() {
               super.onAuthenticationFailed()
               Log.d(TAG, "Authentication failed for an unknown reason")
           }

           override fun onAuthenticationSucceeded(result: BiometricPrompt.AuthenticationResult) {
               super.onAuthenticationSucceeded(result)
               Log.d(TAG, "Authentication was successful")
               processData(result.cryptoObject)
           }
       }

        //The API requires the client/Activity context for displaying the prompt
       val biometricPrompt = BiometricPrompt(this, executor, callback)
       return biometricPrompt
   }
...
}