Override output audio port in iOS 11.3

Question

Is it possible to override audio port to speaker(

[[AVAudioSession sharedInstance] overrideOutputAudioPort:AVAudioSessionPortOverrideSpeaker error:nil]

) when device is connected to external screen via airplay, it worked on iOS 11.2 and earlier, but on iOS 11.3 it doesn't?

Answer 1

In my experience that's not enough: you also have to set the AVAudioSession category to playAndRecord. This is suggested in the docs for the overrideOutputAudioPort: method:

If your app uses the playAndRecord category, calling this method with the AVAudioSession.PortOverride.speaker causes the system to route audio to the built-in speaker and microphone regardless of other settings. This change remains in effect only until the current route changes or you call this method again with the AVAudioSession.PortOverride.none option.

If you would prefer to permanently enable this behavior, you should instead set the category's defaultToSpeaker option. Setting this option will always route to the speaker rather than receiver if no other accessory such as headphones are in use.

Note that those docs specify that that is sufficient. I don't know if it's necessary: I just haven't found other options that work as reliably.

However, the docs for defaultToSpeaker do say that it's only usable with the AVAudioSessionCategoryPlayAndRecord category.

So, doing the following works for me:

let audioSession = AVAudioSession.sharedInstance()
do {
    try audioSession.setCategory(.playAndRecord, mode: .default)
    try audioSession.overrideOutputAudioPort(.speaker)
} catch {
    print("Error occurred: \(error.localizedDescription)")
}