These scenarios require three individual components:
Unfortunately, this scenario isn’t standardized by the
NFC Forum – therefore, many companies come up with their own approaches. This article provides more background information on how to create a tag that is directly associated with your specific app and works on as many platforms as possible.
Alternatives: On the Windows platform, you also have the option to use a custom URI protocol – see the article
How to Launch Apps via Proximity APIs (NFC) for more information. Custom URI schemes have the advantage that they’re easier for cross-platform scenarios; the downside is that a custom URI scheme is not unique to your app; any other competitor can register
its app for the same URI scheme, causing the user to find multiple apps in the store when they tap your tag.
This section gives an overview of the different approaches on how to create a LaunchApp tag, followed by a section on how to combine the individual records to a single tag.
Microsoft defined the
LaunchApp NDEF record (Type: “windows.com/LaunchApp”, Type Name Format: Absolute URI).
It contains launch parameters that will be passed to the application, and allows specifying any number of platforms and the respective app IDs (used to find the app in the store, as well as to launch it). A major limitation is that this records needs to
be the first record in the NDEF message; otherwise, it will not be handled by the Windows OS. You can find more information in
While this format would allow to be extended with other platforms, no current other operating system is handling these records.
Symbian allows registering an app for a custom record type (Type: custom – e.g., “nokia.com:nfcinteractor”, Type Name Format: External RTD). Custom data for the application can be stored as the payload of the custom record.
This record doesn’t enable linking to the store for downloading the app; the custom record is only recognized if an app registered for a specific custom type during its installation. Therefore, you would typically put two records on the tag: the first one
being the custom record that is linked to your app, plus a second record a standard URL / Smart Poster record that links to your homepage or the store. If the phone already has the app installed, it will recognize the first, custom record and launch your app.
If the app isn’t installed, the phone will skip the (unknown) first record, proceed to the second record (the homepage / store URL) and open the browser / store client to let the user download the app.
More information on registering for custom record types:
App Autostart on NFC Tag Touch (Nokia Developer Blogs).
Starting with Android 4.x, Google introduced the
Android Application Record (AAR) format (Type: “android.com:pkg”, Type Name Format: External RTD). The payload of the record contains the name of the package, which is used by the operating system to launch the already installed app, or to search for it
in the Play Store.
Google recommends to put this record last in the message, to enable compatibility for phones that do not understand this record type and start parsing from the beginning. So you would typically add a URL record that links to your homepage for phones that
do not understand the AAR, and/or a custom record that contains data that will be read by your application.
As described, various operating systems follow different approaches for directly launching apps from a tag. Fortunately, there is a way to combine all different records into a single tag, to create a cross-platform tag that directly launches your app on
Windows, Symbian and Android, plus it contains a URI to link to your website for phones that do not understand one of the other schemes present on your tag.
For this tag to work, the specific order of the records in the message is of importance. By combining 4 records into a single message, the size requirements are considerable; in typical situations, the message will require at least a writable space on the
tag of 250+ bytes.
This schematic visualizes how to store the records on the tag:
How to write such a tag? Windows Proximity APIs can write a LaunchApp tag, but don’t support including this record into a NDEF message that additionally contains other records.
The NDEF library for Proximity APIs includes a class that can create a LaunchApp record and embed it into a bigger NDEF message. Therefore, use the library in order to create a cross-platform LaunchApp tag – it also
includes support for creating custom, URI and Android Application Records.
For an overview of the Proximity APIs and how to read and write tags, read the article
How to Acquire and Publish Content from / to NFC Tags and Proximity Peers.
To find out more about Proximity APIs, check out the
API documentation. More information about how LaunchApp tags are actually formatted as the raw tag contents, is contained in the specification for Proximity driver implementers.
If you’d like to create an NDEF message & LaunchApp record with the Proximity APIs without having to read all the
NDEF specifications, you can simply use the
NDEF Library for Proximity APIs, which include ready-made convenience classes for creating all kinds of records and messages.