With WiFi direct, the devices must pair in a manner similar to an initial Bluetooth pairing.

Apple simplifies this stage.

ISTR around something like the Galaxy Nexus Google doing demos of beaming files between devices via WiFi Direct after having exchanged info with an NFC tap.

But that was just before they decided everything had to go via their cloud.

Curiously if you used a London bus in around 2005 with bluetooth on you would experience a lot of files being sent to you via ad hoc networks.