gistfile1.m

- (BOOL) isPowerConnected
{
    // Temporarily enable battery monitoring to check battery state 
    [UIDevice currentDevice].batteryMonitoringEnabled = YES; 
    BOOL result = ([UIDevice currentDevice].batteryState != UIDeviceBatteryStateUnplugged); 
    [UIDevice currentDevice].batteryMonitoringEnabled = NO; 
    return result
}

// Use this in another method
if (isPowerConnected) 
{ 
    // Do something here which only work when the power is connected.
    // For example disable idle timer only when connected to power 
    [UIApplication sharedApplication].idleTimerDisabled = YES; 
}