Is there an event for when the headphones are unplugged? - iphone

Question

During a test, a client noticed that video playback in the iPhone pauses when headphones are unplugged. He wanted similar functionality for audio playback, and maybe the ability to pop up a message.
Does anyone know if there's an event of some kind I could hook into to make this possible?

Answer 1

See Responding to Route Changes from the Audio Session Programming Guide.

Answer 2

This changed with iOS 7, you just need to listen to the notification named AVAudioSessionRouteChangeNotification
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(audioRouteChanged:) name:AVAudioSessionRouteChangeNotification object:nil];

Answer 3

Swift 3.0 #snakeoil's solution:
NotificationCenter.default.addObserver(self, selector: #selector(YourViewController.yourMethodThatShouldBeCalledOnChange), name: NSNotification.Name.AVAudioSessionRouteChange, object: nil)

Answer 4

Here's the full implementation I eventually used for sending events when the headphones are plugged in (and unplugged).
There was a fair amount of complexity I needed to deal with to ensure things still worked after the app was returned from the background.
CVAudioSession.h file
#import <Foundation/Foundation.h>
#define kCVAudioInputChangedNotification #"kCVAudioInputChangedNotification"
#define kCVAudioInterruptionEnded #"kCVAudioInterruptionEnded"
#interface CVAudioSession : NSObject
+(void) setup;
+(void) destroy;
+(NSString*) currentAudioRoute;
+(BOOL) interrupted;
#end
CVAudioSession.m file
#import "CVAudioSession.h"
#import <AudioToolbox/AudioToolbox.h>
#implementation CVAudioSession
static BOOL _isInterrupted = NO;
+(void) setup {
NSLog(#"CVAudioSession setup");
// Set up the audio session for recording
OSStatus error = AudioSessionInitialize(NULL, NULL, interruptionListener, (__bridge void*)self);
if (error) NSLog(#"ERROR INITIALIZING AUDIO SESSION! %ld\n", error);
if (!error) {
UInt32 category = kAudioSessionCategory_RecordAudio; // NOTE CANT PLAY BACK WITH THIS
error = AudioSessionSetProperty(kAudioSessionProperty_AudioCategory, sizeof(category), &category);
if (error) NSLog(#"couldn't set audio category!");
error = AudioSessionAddPropertyListener(kAudioSessionProperty_AudioRouteChange, propListener, (__bridge void*) self);
if (error) NSLog(#"ERROR ADDING AUDIO SESSION PROP LISTENER! %ld\n", error);
UInt32 inputAvailable = 0;
UInt32 size = sizeof(inputAvailable);
// we do not want to allow recording if input is not available
error = AudioSessionGetProperty(kAudioSessionProperty_AudioInputAvailable, &size, &inputAvailable);
if (error) NSLog(#"ERROR GETTING INPUT AVAILABILITY! %ld\n", error);
// we also need to listen to see if input availability changes
error = AudioSessionAddPropertyListener(kAudioSessionProperty_AudioInputAvailable, propListener, (__bridge void*) self);
if (error) NSLog(#"ERROR ADDING AUDIO SESSION PROP LISTENER! %ld\n", error);
error = AudioSessionSetActive(true);
if (error) NSLog(#"CVAudioSession: AudioSessionSetActive (true) failed");
}
}
+ (NSString*) currentAudioRoute {
UInt32 routeSize = sizeof (CFStringRef);
CFStringRef route;
AudioSessionGetProperty (kAudioSessionProperty_AudioRoute,
&routeSize,
&route);
NSString* routeStr = (__bridge NSString*)route;
return routeStr;
}
+(void) destroy {
NSLog(#"CVAudioSession destroy");
// Very important - remove the listeners, or we'll crash when audio routes etc change when we're no longer on screen
OSStatus stat = AudioSessionRemovePropertyListenerWithUserData(kAudioSessionProperty_AudioRouteChange, propListener, (__bridge void*)self);
NSLog(#".. AudioSessionRemovePropertyListener kAudioSessionProperty_AudioRouteChange returned %ld", stat);
stat = AudioSessionRemovePropertyListenerWithUserData(kAudioSessionProperty_AudioInputAvailable, propListener, (__bridge void*)self);
NSLog(#".. AudioSessionRemovePropertyListener kAudioSessionProperty_AudioInputAvailable returned %ld", stat);
AudioSessionSetActive(false); // disable audio session.
NSLog(#"AudioSession is now inactive");
}
+(BOOL) interrupted {
return _isInterrupted;
}
// Called when audio is interrupted for whatever reason. NOTE: doesn't always call the END one..
void interruptionListener( void * inClientData,
UInt32 inInterruptionState) {
if (inInterruptionState == kAudioSessionBeginInterruption)
{
_isInterrupted = YES;
NSLog(#"CVAudioSession: interruptionListener kAudioSessionBeginInterruption. Disable audio session..");
// Try just deactivating the audiosession..
OSStatus rc = AudioSessionSetActive(false);
if (rc) {
NSLog(#"CVAudioSession: interruptionListener kAudioSessionBeginInterruption - AudioSessionSetActive(false) returned %.ld", rc);
} else {
NSLog(#"CVAudioSession: interruptionListener kAudioSessionBeginInterruption - AudioSessionSetActive(false) ok.");
}
} else if (inInterruptionState == kAudioSessionEndInterruption) {
_isInterrupted = NO;
// Reactivate the audiosession
OSStatus rc = AudioSessionSetActive(true);
if (rc) {
NSLog(#"CVAudioSession: interruptionListener kAudioSessionEndInterruption - AudioSessionSetActive(true) returned %.ld", rc);
} else {
NSLog(#"CVAudioSession: interruptionListener kAudioSessionEndInterruption - AudioSessionSetActive(true) ok.");
}
[[NSNotificationCenter defaultCenter] postNotificationName:kCVAudioInterruptionEnded object:(__bridge NSObject*)inClientData userInfo:nil];
}
}
// This is called when microphone or other audio devices are plugged in and out. Is on the main thread
void propListener( void * inClientData,
AudioSessionPropertyID inID,
UInt32 inDataSize,
const void * inData)
{
if (inID == kAudioSessionProperty_AudioRouteChange)
{
CFDictionaryRef routeDictionary = (CFDictionaryRef)inData;
CFNumberRef reason = (CFNumberRef)CFDictionaryGetValue(routeDictionary, CFSTR(kAudioSession_AudioRouteChangeKey_Reason));
SInt32 reasonVal;
CFNumberGetValue(reason, kCFNumberSInt32Type, &reasonVal);
if (reasonVal != kAudioSessionRouteChangeReason_CategoryChange)
{
NSLog(#"CVAudioSession: input changed");
[[NSNotificationCenter defaultCenter] postNotificationName:kCVAudioInputChangedNotification object:(__bridge NSObject*)inClientData userInfo:nil];
}
}
else if (inID == kAudioSessionProperty_AudioInputAvailable)
{
if (inDataSize == sizeof(UInt32)) {
UInt32 isAvailable = *(UInt32*)inData;
if (isAvailable == 0) {
NSLog(#"AUDIO RECORDING IS NOT AVAILABLE");
}
}
}
}
#end