iPhone NFC Activation
The more recent models of iPhone use what is called Background Tag Reading.This means that as long as the iPhone screen is on, your NFC Tag Reader is active and can read NFC tags if you place your iPhone nearby.
Older models of iPhone require you to turn on the NFC Tag Reader manually in order for you to use NFC.
To turn on the NFC Tag Reader on older iPhones:
Step 1: If you have an iPhone 8 or iPhone 7, swipe up from the bottom of the screen to open the Control Center.
Step 2: If you have an iPhone X, swipe down from the top right-hand corner of the screen to open the Control Center.
Step 3: Tap theNFC Tag Readericon to turn on NFC. You can now use NFC to interact with other devices or tags.
Step 4: If you don’t see theNFC Tag Readericon in Control Center on iPhone 7, 8, or X, you’ll need to add it to your Control Center through Settings.
Step 5: Open theSettingsapp.
Step 6: TapControl Center.
Step 7: Scroll down to theMore Controlssection and tap thePlus (+)icon next toNFC Tag Reader.
Step 8: Repeat Steps 1-3.
(Steps Taken from GroovyPost.com)