How to change iPhone APN (Access Point Name) programmatically?
Or force a 3G/GPRS connection to use certain APN programmatically?
Can't be done with the SDK. Third-party apps don't get that level of control over the hardware, especially not the cell modem.
browse to unlockit.co.nz from your phone. it can change the apn to any predetermined or custom APN on any unlocked iphone
来源：https://stackoverflow.com/questions/2665356/how-to-change-iphone-apn-access-point-name-programmatically