The iOS Core NFC Framework limits the iPhone to read-only operations of NFC Tags and devices. To write NFC Tags for use with the iPhone, or other NFC reader device, you can use an USB NFC Reader/Writer device attached to your Mac. We have been overwhelmed with downloads and interest in the NFC Mac App since the announcement of iPhone support for NFC. The following set of NFC Readers can be used with the Mac App. ACS (Advanced Card Systems) ACS ACR122U (NFC Type I-IV, DESFire, MIFARE) ACS ACR1252U (NFC Type I-IV, DESFire, MIFARE) ACS ACR1255U-J1 (NFC Type I-IV, DESFire, MIFARE) HID Global HID OMNIKEY 5022 (NFC Type II & Type IV, DESFire, MIFARE) IDENTIVE IDENTIVE uTrust 370x (NFC Type II & Type IV, DESFire, MIFARE) This list is limited by verification testing, and unique engineering necessary to interoperate with the hardware. These readers are readily available on Amazon, or direct-from manufacturer outlets. The Mac App is a nice compliment to t