I would like to install a system that would check attendance using an RFID reader, and an IOS application that would fetch and manipulate data. If this is possible, what type of server could link the reader and IOS app?
There is no single server or database system that you would need to use. You would have to choose the right reader for your particular application and then work with the reader company to enable data captured by the device to be exported to a database. Then you would need to develop an app that could analyze the information in the database however you want it to be analyzed. Some readers employ the Low Level Reader Protocol (LLRP) developed by EPCglobal (see LLRP Toolkit). Some interrogators have proprietary interfaces. Talk to the reader company about the best way to get the data into your database.
—Mark Roberti, Founder and Editor, RFID Journal
Can I Link an RFID Reader to a Database? »