Create an adhoc wifi network using your mac
Instructions for creating an adhoc wifi network to share files between iOS devices and Macs even without an external router
Turn AirPort off.
Open Open System Preferences -> Sharing and select “Internet Sharing”.
Under “Share your internet from:”, select “Ethernet” — or whatever’s available. Anything EXCEPT “AirPort”.
Under “To computers using”, check “AirPort”
Click on the Internet Sharing checkbox to the left to turn sharing on.
Turn AirPort back on. Your MacBook is now, effectively, a WiFi router.
Go to your iPhone’s Settings -> WiFi. It should be showing a Network name that reflects the name of your MacBook. Sometimes it takes a few moments for the new network to show up.
This will establish a local area network (LAN) that includes the MacBook and the iPhone. If you run DropCopy on both, you’ll be able to share files.