[Fix] Allow navigation to be spoken when device is on silent

[chriswebb09]

Description

This is a fix so that the sample speaks navigation instructions when the device is on silent

Linked Issue(s)

• swift/issues/7556

[yo1995]

I don't have an iOS 26 device.
Is this problem reproducible on iOS 26 Simulator? I turned on silent mode on simulator, and with or without the fix, the voice guidance are both announced.

[yo1995]

1. Can you try if voicePrompt needs to be set with the setCategory(_:mode:options:) method?
   1. If so, does the mode need to be reset to default after the sample is closed?
2. The method is called each time when a voice guidance is available. Instead of setting the shared audio session for each voice guidance, can you set it only once, before the turn-by-turn navigation starts?
3. The samples app doesn't print error. It uses errorAlert(presentingError:) to present errors. Handle the error in the view.
4. Once addressed the feedback, can you add some comments to explain what do these changes do? Thanks.

[des12437]

I don't have an iOS 26 device. Is this problem reproducible on iOS 26 Simulator? I turned on silent mode on simulator, and with or without the fix, the voice guidance are both announced.

I tested this on an iOS 26 device and without the fix the directions are not spoken when the device is on silent mode, with the fix the directions are spoken regardless.

[des12437]

In addition to the other feedback, a variable can be created for the session, the .playback category is implicit, and the error can be set so it is shown in the error alert UI:

do {
     let session = AVAudioSession.sharedInstance()
     try session.setCategory(.playback)
     try session.setActive(true)
} catch let error as NSError {
     self.error = error
}