Link HUB NFC Frequently Asked Questions

What’s a NFC tag?
Near Field Communication tags are inexpensive wireless gadgets that allow the transfer of data (text, website URLs, numbers, etc.) between two NFC enabled devices such as the tag itself and a phone.
Often in the format of stickers, they contain a small microchip with little antennas and no battery (they’re powered by the other device they’re interacting with, such as the phone… sorcery!); they can store a very small amount of data, but still enough to be useful.

Why should I use a NFC tag?
You might find a NFC tag useful for triggering some kind of automation.
For instance, you might place a sticker on the dashboard of your car and have your phone automatically perform some actions (start navigation, play some music, message someone, etc.) when you move your phone over it.

How does that work?
NFC tags can be written (encoded) by you with some kind of data that many phones are able to read and react to when they’re placed pretty close (few centimetres). Writing requires 3 things:

  1. A tag that can be written (read only tags exist, and writable tags can be locked and become read only… you need a writable one to encode data on it); you can find some suggestions on purchase strategy, but no endorsements, below.
  2. Something you want to encode on it, such as an URL or some text; you can add multiple “chunks” of data, so writing both a website URL and some text is possible, but how much you can write depends on the size of the tag (many tags can store 130 characters, more than enough for URLs, short texts, phone numbers, etc.).
  3. A phone that support NFC writing and a specific app that does the “encoding” (writing) work.

Which iPhones and iPads do support NFC tag reading and writing?
iPhone 7, 8 and X running iOS 11 or later can read and write NFC tags, but require an app to do so and can’t read tags in background, when that app is not running.
iPhone XS, XS Max, XR, 11, 11 Pro and SE (the new, big one) can read tags even without an app, in background; they obviously can write tags too, but that requires an app.
Currently, no iPad model supports NFC tag reading and writing.

What’s the role of Link HUB in all this?
Starting with version 1.4, Link HUB can read and write NFC tags to trigger the launch of links you saved inside the app just by moving your phone close to a NFC tag that has previously been properly encoded by the app.
For iPhones that support background NFC reading such as the iPhone 11, Link HUB does not need to be running: a notification appears and when you tap it, your link is launched.
For older models such as an iPhone 8, you need to manually open Link HUB and tap the “scan” button in the upper right corner to initiate NFC reading; as soon as the phone reads the tag, the link is opened.
Please know that NFC reading and writing requires a Link HUB Pro subscription, which by the way is really inexpensive at only $ 3.99 per year, and supports development of cool features like this one.

How do I prepare and use a NFC tag with Link HUB?
If you already have a writable tag, the procedure is pretty automatic, actually:

  1. Add any URL to Link HUB, for instance an URL scheme to send a message to a number (i.e. sms:012345678);
  2. Long-press the link cell in the app and select “Associate NFC Tag” from the menu;
  3. Follow the instructions on screen: move your phone close to the tag and wait for the message confirming you that data has been written (it’s really, really fast).
  4. Test it by pressing the scan icon in the upper right corner of Link HUB, next to the plus button; follow the instructions on screen, scan the tag and see your link immediately launched. Then, if your phone supports background reading, return to the home screen and move your iPhone close to the tag in the same way you did before: a notification will appear, and when you tap it, the link will be immediately launched.

This seems cool. Where do I buy NFC Tags? What if I want to learn more?
This post on Seritag is packed with useful informations.
Myself, I purchased very inexpensive tags with NXP NTAG213 chips on Amazon and they are working like a charm; I’m actually not an expert of “hardware” NFC, so I can only tell you that chip model is working well for me and costed around $ 15 for a pack of 10. I’m not willing to sponsor any product, nor I am providing any specific affiliate link, as your mileage may vary with this kind of inexpensive products, but again I have had a good experience with these. In all cases, my main recommendation is to check that someone already reviewed the tag you’re considering and said they’re successfully using them with an iPhone.

Any other suggestions on tags’ hardware?
Mainly, two:

  1. Don’t place your tags on metal surfaces unless they are specifically and explicitly coated for that surface; similarly, keep tags dry unless they sell them as waterproof.
  2. Keep some physical distance between tags when reading or writing them.

I deleted a cell in Link HUB and now the tag does not work. What can I do?
Each URL you save in Link HUB has a unique identifier randomly generated by the app and this ID is associated with a tag when you encode it; so, if you delete a Link in the app, the tag won’t trigger that automation anymore.
Just overwrite the tag with a different Link to reuse it.

Are tags “secure”? What happens if a Link HUB-encoded tag is read by another phone that doesn’t have the app installed?
Every phone with NFC capabilities can read a NFC tag if it is close enough, so you need to take that into account and model your security accordingly: you can’t put a private information on a tag in a public space and expect it never be read by someone else.
Having said that, most of the times you won’t write sensible and actionable informations on tags: for instance, if you write the URL to trigger a Shortcut that’s only available on your iPhone, that won’t do anything if someone else reads it using a different app capable of reading NFC tags’ NDEF messages.
Having said this, if a phone reads a tag encoded by Link HUB but does not have the app installed, it will be prompted to visit this webpage, which explains what the app does and suggests to install it; this is useful for you, as your Links sync with iCloud between devices and therefore the encoded URL and its unique identifier will sync on your new device making you able to use that tag right away, while for another person that UUID will do nothing, so the app will only launch when reading the tag without performing any action.

What if I want to write NFC tags with another app and read them with Link HUB?
First, why? Link HUB can write tags with the proper format it needs to read them later, associating a tag with a specific Link.
But again, you might have your reasons, and it is possible to write tags with a different app and still have them work with Link HUB; please know that no support is provided if you decide to try this, as there are too many untestable variables.
If you really want to do it, you’ll need to write a NDEF message with 2 separate chunks of data:

  1. This exact URL: https://cdf1982.com/link-hub/nfc-tag
  2. A text string with this format: linkhub_UNIQUE-IDENTIFIER-COPIED-FROM-LINKHUB, where you replace “UNIQUE-IDENTIFIER-COPIED-FROM-LINKHUB” with the number you can copy by long pressing a cell in the app and selecting “Copy unique identifier” from the menu. No spaces, the string must begin with linkhub followed by and underscore and then the ID the app copies for you.