.. _NFC:

NCF communication
=================

On iOS, NFC operations are restricted by the system. They can only be performed after a system call when a pop-up displayed on the screen. That is why specific API functions must be used to read tokens with NFC.

Using NFC readers on iOS
------------------------

Note that iOS NFC Tag Reader Session is supported in: iPhone XR, iPhone X, iPhone XS, iPhone XS Max, iPhone 11, iPhone 11 Pro. (iOS 13)

If the creation of the environment was successful (:js:class:`SCWS.create`) and the device supports NFC Tag Reader Session, a :js:class:`Reader` named ``NFC Interface`` will be added to the list of the readers (:js:class:`SCWS.readers`).

To get the NFC (:js:class:`Reader`), call (:js:class:`SCWS.getReader`) by passing ``NFC Interface`` as parameter. For (:js:class:`Reader`) objects with :js:class:`Reader.requiresNfcTagReaderSession` returns ``true``, you must use the functions below. 

To start scanning for NFC Tags, call (:js:class:`SCWS.initNfcTagReaderSession`). iOS will display an alert action sheet waiting to detect tags. When a tag is detected, your app will receive a (:js:class:`SCWS.onreaderstatechanged`) event.

When your app is done communicating with the card or if an error occurred, call (:js:class:`SCWS.endNfcTagReaderSession`). It will end the NFC Tag Reader Session, dismiss the alert action sheet and display a message error or a positive check mark to the user. 

.. js:autofunction:: SCWS.initNfcTagReaderSession
.. js:autofunction:: SCWS.endNfcTagReaderSession
.. js:autofunction:: SCWS.updateMessageNfcTagReaderSession

Similar behavior on Android
---------------------------
In order to have cross-platform code, a similar behavior can be achieved with the (:js:class:`AndroidNfcOverlay`) class.

For example code to implement cross-platform NFC reading code, see :ref:`nfcexample`.