接近感应传感器

[[UIDevice currentDevice] setProximityMonitoringEnabled:YES];
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(sensorStateChange:)
                                                 name:@"UIDeviceProximityStateDidChangeNotification"
                                               object:nil];

-(void)sensorStateChange:(NSNotificationCenter *)notification;
{
    if ([[UIDevice currentDevice] proximityState] == YES) {
        NSLog(@"Device is close to user");
    }else{
        NSLog(@"Device is not close to user");
    }
}