I'm new to NFC technology.
Apple hasn't yet opened NFC for developers. Does this mean that 3rd party application can't write data or trigger an action on the device?
But is it possible to identify the watch using an RFID reader similar to a smart card?
This is possible using a Apple Wallet Pass with NFC support. These require special approval from Apple but allow an Apple Watch or iPhoneSE/6/6s/6+/7/7+ to present a unique identifier to an NFC reader. Privacy may be a concern but the Value Add Services (VAS) protocol that Apple opted for in their NFC implementation allows for the NFC reader to query for a target pass specifically. Together with a native app, this feature can loopback a notification to the Watch/iPhone via Bluetooth or Push Notification for a proof of intent style experience.
To get this to work you will need an NFC reader implementing Enhanced Contactless Polling (along with the Wallet NFC-enabled Pass). Flomio offers a line of mobile and PC compatible NFC readers that you may consider. More details on the how to deploy solutions of this type, check out this thread.
来源：https://stackoverflow.com/questions/31480805/is-apple-watch-detected-by-an-rfid-reader