The easiest way of doing this will be to use wifi of course. You will need to determine if your wifi base acts as a hub or a switch. If it acts as a hub then just connect your windows pc to it and wireshark should be able to see all the traffic from the iPhone. If it is a switch then your easiest bet will be to buy a cheap hub and connect the wan side of your wifi base to the hub and then connect your windows pc running wireshark to the hub as well. At that point wireshark will be able to see all the traffic as it passes over the hub.
