How to Route Audio to Speaker Without Using Audiosessionsetproperty

How Do I Route Audio to Speaker without using AudioSessionSetProperty?

On each release of iOS, more of the audioSession properties are migrated to AVFoundation, so you should use those in preference whenever available.

Since iOS 6 kAudioSessionProperty_OverrideAudioRoute is represented in AVAudioSession by the method

- (BOOL)overrideOutputAudioPort:error:

Available values are AVAudioSessionPortOverrideNone and AVAudioSessionPortOverrideSpeaker

Here is an example audio session configured entirely via AVFoundation:

 - (void)configureAVAudioSession
{
   // Get your app's audioSession singleton object
    AVAudioSession *session = [AVAudioSession sharedInstance];

    // Error handling
    BOOL success;
    NSError *error;

    // set the audioSession category. 
    // Needs to be Record or PlayAndRecord to use audioRouteOverride:  

    success = [session setCategory:AVAudioSessionCategoryPlayAndRecord
                             error:&error];

   if (!success) {
       NSLog(@"AVAudioSession error setting category:%@",error);
   }

    // Set the audioSession override
    success = [session overrideOutputAudioPort:AVAudioSessionPortOverrideSpeaker
                                          error:&error];
    if (!success) {
        NSLog(@"AVAudioSession error overrideOutputAudioPort:%@",error);
    }

    // Activate the audio session
    success = [session setActive:YES error:&error];
    if (!success) {
        NSLog(@"AVAudioSession error activating: %@",error);
    }
    else {
         NSLog(@"AudioSession active");
    }

}

UPDATE

Since iOS 7.0, the Audio Session Services C API is now fully deprecated in favour of AVAudioSession.

UPDATE 2

- (BOOL)overrideOutputAudioPort:error:  

is a method, not a property, and it sets an underlying write-only UInt32 value. You can't get the current value, and you should treat the method as setting a temporary state. If the audio route changes or is interrupted, the property resets to its default (AVAudioSessionPortOverrideNone). You can get interruption notifications via AVAudioSessionDelegate.

How to route to kAudioSessionProperty_OverrideCategoryEnableBluetoothInput without using AudioSessionSetProperty

To expand on my previous answer and comment:

You would use the AVAudioSession method

- (BOOL)setCategory:(NSString *)category 
        withOptions:(AVAudioSessionCategoryOptions)options 
              error:(NSError **)outError 

with category as

AVAudioSessionCategoryPlayAndRecord

or AVAudioSessionCategoryRecord

and options as

AVAudioSessionCategoryOptionAllowBluetooth

In your reply you say

that is not the same because that would allow A2DP bluetooth only

But according to the Apple docs

AVAudioSessionCategoryOptionAllowBluetooth

Allows Bluetooth handsfree devices to appear as available input routes.

I understand that to mean bluetooth HFP, which I presume is what you are after. As regards "forcing", Apple is not too keen on apps forcing/overriding OS control of a user's experience of device behaviour.

It may be that this does not work in practice - I have not been able to test it. Presumably you have, and it fails (you don't indicate in your question). But you are hitting the limits of Apple's documentation on this issue. If you really can't get it to work I would be inclined to go with the deprecated C interface, and be prepared to make changes for iOS8.

Routing iPhone Audio Sound

To do this you have to add property listener when you setup audio session:

AudioSessionAddPropertyListener(kAudioSessionProperty_AudioRouteChange, audioSessionPropertyListener, nil);

Where

void audioSessionPropertyListener(void* inClientData, AudioSessionPropertyID inID,
                                          UInt32 inDataSize, const void* inData) {
          UInt32 audioRouteOverride = kAudioSessionOverrideAudioRoute_Speaker;

          if (!isHeadsetPluggedIn()) 
            AudioSessionSetProperty (kAudioSessionProperty_OverrideAudioRoute,sizeof (audioRouteOverride),&audioRouteOverride);
        }

BOOL isHeadsetPluggedIn() {
  UInt32 routeSize = sizeof (CFStringRef);
  CFStringRef route;

  OSStatus error = AudioSessionGetProperty (kAudioSessionProperty_AudioRoute,
                                            &routeSize,
                                            &route
                                            );



     if (!error && (route != NULL) && ([(NSString*)route rangeOfString:@"Head"].location != NSNotFound)) {
        NSLog(@"HeadsetPluggedIn");
        return YES;
      }
      NSLog(@"Headset_NOT_PluggedIn");
      return NO;
    }

So when headphones are plugged in or out you get a notification and change audio output direction.

Routing iPhone Audio Sound

To do this you have to add property listener when you setup audio session:

AudioSessionAddPropertyListener(kAudioSessionProperty_AudioRouteChange, audioSessionPropertyListener, nil);

Where

void audioSessionPropertyListener(void* inClientData, AudioSessionPropertyID inID,
                                          UInt32 inDataSize, const void* inData) {
          UInt32 audioRouteOverride = kAudioSessionOverrideAudioRoute_Speaker;

          if (!isHeadsetPluggedIn()) 
            AudioSessionSetProperty (kAudioSessionProperty_OverrideAudioRoute,sizeof (audioRouteOverride),&audioRouteOverride);
        }

BOOL isHeadsetPluggedIn() {
  UInt32 routeSize = sizeof (CFStringRef);
  CFStringRef route;

  OSStatus error = AudioSessionGetProperty (kAudioSessionProperty_AudioRoute,
                                            &routeSize,
                                            &route
                                            );



     if (!error && (route != NULL) && ([(NSString*)route rangeOfString:@"Head"].location != NSNotFound)) {
        NSLog(@"HeadsetPluggedIn");
        return YES;
      }
      NSLog(@"Headset_NOT_PluggedIn");
      return NO;
    }

So when headphones are plugged in or out you get a notification and change audio output direction.

AVAudioPlayer via Speakers

I used the AudioToolbox framework that's why I initialized my audio session as following:

AudioSessionInitialize(NULL, NULL, NULL, NULL);

Here's the rest of my code that I used to configure the audio session. I didn't override the audio route and I also think this is not necessary.

UInt32 sessionCategory = kAudioSessionCategory_MediaPlayback;
OSStatus err = AudioSessionSetProperty(kAudioSessionProperty_AudioCategory,
                                       sizeof(sessionCategory),
                                       &sessionCategory);
AudioSessionSetActive(TRUE);
if (err) {
    NSLog(@"AudioSessionSetProperty kAudioSessionProperty_AudioCategory failed: %d", err);
}

how to route iPhone audio to the bluetooth headset

This little test worked for me... it involves setting up the bluetooth headset as the input also (not sure if that's what you want). Sorry about the crappy formatting on the code...

// create and set up the audio session
AVAudioSession* audioSession = [AVAudioSession sharedInstance];
[audioSession setDelegate:self];
[audioSession setCategory: AVAudioSessionCategoryPlayAndRecord error: nil];
[audioSession setActive: YES error: nil];

// set up for bluetooth microphone input
UInt32 allowBluetoothInput = 1;
OSStatus stat = AudioSessionSetProperty (
                         kAudioSessionProperty_OverrideCategoryEnableBluetoothInput,
                         sizeof (allowBluetoothInput),
                         &allowBluetoothInput
                        );
NSLog(@"status = %x", stat);    // problem if this is not zero

// check the audio route
UInt32 size = sizeof(CFStringRef);
CFStringRef route;
OSStatus result = AudioSessionGetProperty(kAudioSessionProperty_AudioRoute, &size, &route);
NSLog(@"route = %@", route);    
// if bluetooth headset connected, should be "HeadsetBT"
// if not connected, will be "ReceiverAndMicrophone"

// now, play a quick sound we put in the bundle (bomb.wav)
CFBundleRef mainBundle = CFBundleGetMainBundle();
CFURLRef        soundFileURLRef;
SystemSoundID   soundFileObject;
soundFileURLRef  = CFBundleCopyResourceURL (mainBundle,CFSTR ("bomb"),CFSTR ("wav"),NULL);
AudioServicesCreateSystemSoundID (soundFileURLRef,&soundFileObject);
AudioServicesPlaySystemSound (soundFileObject);     // should play into headset

Hope that helps!

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