iPhone4 how to find out if the power cable is plugged in?

Question

I would like to know if my app is running with an external power cable attached. Is it possible to find out this state at runtime?

An extra question: would this be able to differentiate between true USB power and those external "battery packs"?

Thank you!

Answer 1

Use UIDevice property batteryState:

[[UIDevice currentDevice] batteryState] == UIDeviceBatteryStateCharging

From UIDevice Docs:

typedef enum {
    UIDeviceBatteryStateUnknown,
    UIDeviceBatteryStateUnplugged,
    UIDeviceBatteryStateCharging,
    UIDeviceBatteryStateFull,
} UIDeviceBatteryState;

As for your 2nd question. I don't believe you can determine any difference between a battery pack and a wall charger since the above UIDeviceBatteryState flags are the only "states" a device battery can report. So both a battery pack and wall charger would appear as either UIDeviceBatteryStateCharging or UIDeviceBatteryStateFull (or UIDeviceBatteryStateUnplugged if the battery pack is plugged in but out of juice).