I wish I could this holiday to share my internet data mobile from my iPhone to the Pi.
These steps from Dave Conroy will help us to achieve this.
Never hurts to have this information closely. The good thing is that with this guide, do not need to run anything once you connect your iPhone to the Pi. It will automatically connect and have internet.
To do this, the first step is to install a number of packages for the Raspi to detect the device. After setting the file /etc/network/interfaces, we have internet through the iPhone in the graphical environment.
To get it from console, you must be follow a few steps more.
By the way, I recommend you to take a look at other articles he have on his blog.