The first issue is like the difference between a “blank” floppy disk and an “unformatted” one.
The blank NFC tags that you buy from Amazon are typically pre-formatted. They are ready to be written on and they have some information which says “I am a blank tag in X format.“
NFC tags can use different data formats, but the one that is used for most mobile phone or tablet applications is NDEF (NFC data exchange format).
This means the tag will have a specific ID and records will be written to it in a specific format, so they can be easily read by devices that can read NDEF records. These records are called “NDEF messages.“
When you buy a blank tag from Amazon in NDEF format, it already has an ID and it is ready to receive data in that format.
So now what can you do with it? Well that depends on the specific model of your iPhone.
The iOS 14 NFC reader in the control center on An iPhone 8 will ignore a blank NDEF format NFC tags. Which is Probably what has been happening to you.
You need to write a message on it. And on an iPhone 8, you could only do that with a third party app, usually NFC Tagwriter by NXP.
But you can’t write just any gobbledygook. Because then the tag scanner won’t respond either. You have to write an actual actionable NDEF message.
And unless you’re writing your own code, the only one that really makes sense for most people is a “webhook.“ (not “web link.”) The web hook is a URL with some specific parameters built into it which will then cause something to happen when you land on that URL.
So when you say you don’t want to write a web link, you might as well just throw away your NFC tags. There isn’t anything you’ll be able to do with them with an iPhone 8. The only thing the NFC scanner in the control center can do is read the tag and execute that webhook.
But there are definitely people who said “wait, I am not trying to do something over the Internet here.” And Apple did eventually provide that option, but only for phones with iPhone X or higher and only with iOS 14.
Once you have that combination, your iPhone can execute what are called “App Clips” instead of a webhook. An app clip is provided by the creator of a specific app and it’s just a way to trigger that app from an NFC tag or QR code. The official Apple shortcuts feature can do this, which is what most people do for Home Automation. But there are some other apps that can also do it. For example, Phillips hue and LIFX have their own App Clips.
But in order to make that work, something still has to write to the NFC tag one time to store the information about the App Clip In an NDEF message. Then after that, whenever you put your iPhone X or higher near the NFC tag, the app clip will be initiated.
Normally the app creators will have instructions for you about how to set this up. (Or they sell their own NFC tags which already have the correct message written on them.) But again, people Who don’t write their own code usually just use the built-in Apple Shortcuts feature.
So…
An NFC tag Has to be formatted before it can be read.
The NFC tag blanks that you buy from Amazon are usually pre-formatted to use the NDEC format.
That’s all you need if you have at least an iPhone X running iOS 14.
But if you have an older iPhone, you will have to use a third-party app to write the NDEC message to the tag which will tell the iPhone what to do when it reads the tag. Otherwise just nothing happens.
The following page has more details on the different iPhone model capabilities:
This should be a sticky!