User guide

[[NSNotificationCenter defaultCenter] addObserver:self

selector:@selector(handleRouteChange:)

name:AVAudioSessionRouteChangeNotification

object:session];

[session setActive:YES error:&audioSessionError];

if (audioSessionError) {

NSLog(@"Error %ld, %@, (long)audioSessionError.code,

audioSessionError.localizedDescription);

}

sampeRate = session.sampleRate;

bufferDuration = session.IOBuffferDuration;

NSLog(@"Sampe Rate:%0.0fHZ I/O Buffer Duration:%f", sampleRate, bufferDuration);

Querying Hardware Characteristics

Hardware characteristics of an iOS device can change while your app is running, and can differ from device to

device. When you use the built-in microphone for an original iPhone, for example, recording sample rate is

limited to 8 kHz; attaching a headset and using the headset microphone provides a higher sample rate. Newer

iOS devices support higher hardware sample rates for the built-in microphone.

Your app’s audio session can tell you about many hardware characteristics of a device. These characteristics

can change at runtime. For instance, input sample rate may change when a user plugs in a headset. See

AVAudioSession Class Reference for a complete list of properties.

Before you specify preferred hardware characteristics, ensure that the audio session is inactive. After establishing

your preferences, activate the session and then query it to determine the actual characteristics. This final step

is important because in some cases, the system cannot provide what you ask for.

Optimizing Your App for Device Hardware

Querying Hardware Characteristics