On iPhones, the NFC antenna is generally located at the top-center of the device, near the front-facing camera or the Apple logo on the back, depending on the model:
For iPhones, hold the top-back portion of the device near the NFC tag and gently adjust position until it reads. Tips include:
NFC is automatically enabled on iPhones that support it. However, for manual scanning:
To add the icon to Control Center: