AVSpeechSynthesizer stopped after receiving audio interruption notification

Question

I made an application that can speak a word (TTS) in the background.

But the player will be stopped after receiving this notice of interruption.

AVSpeechSynthesizer Audio interruption notification: {
    AVAudioSessionInterruptionTypeKey = 1;
    AVAudioSessionInterruptionWasSuspendedKey = 1; 
}

After I found the solution here, which is shown below, adding a notification and implementing the following code.

However, I found that it AVAudioSessionInterruptionTypeEndedwould never appear. Even I laid the foundation for a function AVAudioSessionInterruptionTypeBeganthat still doesn't work.

My question is: how do I keep the AVSpeechSynthesizer running after receiving an interrupt notification?

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleAudioSessionInterruption:) name:AVAudioSessionInterruptionNotification object:aSession];

- (void)handleAudioSessionInterruption:(NSNotification*)notification {

    NSNumber *interruptionType = [[notification userInfo] objectForKey:AVAudioSessionInterruptionTypeKey];
    NSNumber *interruptionOption = [[notification userInfo] objectForKey:AVAudioSessionInterruptionOptionKey];

    switch (interruptionType.unsignedIntegerValue) {
        case AVAudioSessionInterruptionTypeBegan:{
            [self interruptHandler];
            [self playObject];
        } break;
        case AVAudioSessionInterruptionTypeEnded:{
            if (interruptionOption.unsignedIntegerValue == AVAudioSessionInterruptionOptionShouldResume) {
                // Here you should continue playback.
                [self playObject];
            }
        } break;
        default:
            break;
    }
}

- (void) interruptHandler {
    @synchronized (self) {
        dispatch_async(dispatch_get_main_queue(), ^{
            NSError *error;
            AVAudioSession *aSession = [AVAudioSession sharedInstance];
            [aSession setCategory:AVAudioSessionCategoryPlayback withOptions:AVAudioSessionCategoryOptionDefaultToSpeaker error:&error];
            [aSession setMode:AVAudioSessionModeDefault error:&error];
            [aSession setActive: YES error: &error];
        });
    }
}