.. _nfc_launch_app:

Launch App
##########

.. contents::
   :local:
   :depth: 2

The Launch App library provides a way to create NFC messages capable of launching Android or iOS applications.

Overview
********

A Launch App message contains two records: URI record and Android Launch App record.
Typically, the URI record contains a Universal Link used by iOS and the Android record contains an Android package name.
The Universal Link is a link associated to the application.

Implementation
**************

The :ref:`nfc_launchapp_rec` library provides functions for creating the record and the :ref:`nfc_launchapp_msg` library provides functions for creating and encoding the message.

The following code snippets show how to generate a Launch App message.

1. Define the Universal Link string, Android package name string, and create a buffer for the message:

   .. code-block:: c

      /* Package: no.nordicsemi.android.nrftoolbox */
      static const uint8_t android_pkg_name[] = {
               'n', 'o', '.', 'n', 'o', 'r', 'd', 'i', 'c', 's', 'e', 'm', 'i', '.', 'a', 'n', 'd', 'r',
               'o', 'i', 'd', '.', 'n', 'r', 'f', 't', 'o', 'o', 'l', 'b', 'o', 'x' };

      /* URI nrf-toolbox://main/ */
      static const uint8_t universal_link[] = {
               'n', 'r', 'f', '-', 't', 'o', 'o', 'l', 'b', 'o', 'x', ':', '/', '/', 'm', 'a', 'i', 'n',
               '/'};

#. Create the Launch App message:

   .. code-block:: c

      int err;

      err = nfc_launchapp_msg_encode(android_pkg_name,
			            sizeof(android_pkg_name),
			            universal_link,
			            sizeof(universal_link),
			            ndef_msg_buf,
			            &len);

      if (err < 0) {
	      LOG_ERR("Cannot encode message!");
	      return err;
      }

   Provide the following parameters:

    * Android package name string
    * Length of Android package name string
    * Universal Link string
    * Length of the Universal Link string
    * Message buffer
    * Size of the available memory in the buffer


Supported features
******************

The library supports encoding AAR (Android Application Record) and Universal Links into NFC message.

Samples using the library
*************************

You can use this library when building NDEF messages for tag emulation (for example, with the Type 2 or Type 4 Tag libraries).
|BMshort| currently does not provide samples using this library.

Dependencies
************

* :ref:`nfc_uri_msg`
* :ref:`nfc_ndef_msg`
* :ref:`nfc_ndef_record`

API documentation
*****************

.. _nfc_launchapp_msg:

Launch App messages
===================

| Header file: :file:`bm/nfc/ndef/launchapp_msg.h`
| Source file: :file:`subsys/nfc/ndef/launchapp_msg.c`

:ref:`NDEF Launch App messages API reference <nfc_ndef_launchapp_msg>`

.. _nfc_launchapp_rec:

Launch App records
===================

| Header file: :file:`bm/nfc/ndef/launchapp_rec.h`
| Source file: :file:`subsys/nfc/ndef/launchapp_rec.c`

:ref:`NDEF Launch App records API reference <nfc_ndef_launchapp_rec>`