如何检测接近传感器?

How to detect Proximity Sensor?

如何检测用户是否在附近听到此音频?

首先使用iPhone Proximity Sensor检测接近传感器的状态 然后使用 phone 呼叫扬声器 Play audio through upper (phone call) speaker

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