The new iPhone Xs and Xs Max, as well as a colorful family of the new iPhone Xr handsets, include advancements in near-field communication (NFC) technology that allow the handsets to automatically read nearby NDEF (NFC Data Exchange Format) tags and send any collected assets to appropriate apps without needing to open any specific app beforehand.
Before this change, users were required start an NFC reader session from an app.
Introducing Background Tag Reading:
As highlighted in the “What’s New in Core NFC” video available on Apple’s developer site, the Core NFC framework has introduced a brand-new feature, called Background Tag Reading.
A developer document explains how the feature works:
On iPhones that support Background Tag Reading, the system scans for and reads NFC data without requiring users to scan tags using an app. The system displays a pop-up notification each time it reads a new tag. After the user taps the notification, the system delivers the tag data to the appropriate app. If iPhone is locked, the system prompts the user to unlock the phone before providing the tag data to the app.
Background Tag Reading can read NDEF-formatted tags of type 1 to 5.
To prevent potential security issues stemming from background tag reading, explicit user action is required before the system passes any collected NFC data to an app. Specifically, the user must tap the NFC notification in order to avoid performing an action accidentally.
A system like that would allow, say, metro passes to work with a simple tap and go.
According to the iPhone Xs/Xs Max and iPhone Xr tech specs, the handsets support NFC with reader mode and NFC for Apple Pay, like previous models.
If an NFC tag includes an underlying Apple Universal Link URL, iOS will automatically send data to the right app without any intervention on the user’s part. Otherwise, an NFC link is simply passed to Safari. On new iPhones, these embedded links can automatically trigger actions such as starting a HomeKit setup process, preparing a text or a FaceTime call and more.
NFC security and privacy
In terms of strengthening your security and bolstering privacy, iOS is smart enough to prevent Background Tab Reading from working in the following situations:
Device has never been unlocked
Another NFC reader session is active
Camera is recording video
The Wallet app is being used
Apple Pay is being used
Airplane mode is on
In other words, Core NFC reads tags in the background only when your iPhone is in use—i.e. the Lock screen is on, the Home screen is displayed or you’re happening to use an app.