You could add gps as a required device capability simply to exclude devices without the GPS hardware, which would rule out iPod touches.
Edit: Actually, the correct way to do this is to include for the UIRequiredDeviceCapabilities entry (a dictionary), the telephony key with a value of YES, meaning, only devices that support telephony can use the app.
Also, check out the complete reference of what keys are available for use with UIRequiredDeviceCapabilities.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…