iphone - 如何通过扬声器而不是弱得多的耳机播放音频？

Question

我正在学习核心音频。出于某种原因，处理图的声音只能通过微弱的“耳机扬声器”播放(当您将设备放在耳朵上时)，而不是通过 iPhone 的常规扬声器播放。

这是设置 Audio Session 的代码，但我看不到它在哪里配置音频路由:

- (void) setupAudioSession {

    AVAudioSession *mySession = [AVAudioSession sharedInstance];

    // Specify that this object is the delegate of the audio session, so that
    //    this object's endInterruption method will be invoked when needed.
    [mySession setDelegate: self];

    // Assign the Playback category to the audio session.
    NSError *audioSessionError = nil;
    [mySession setCategory: AVAudioSessionCategoryPlayAndRecord//AVAudioSessionCategoryPlayback
                     error: &audioSessionError];

    if (audioSessionError != nil) {

        NSLog (@"Error setting audio session category.");
        return;
    }

    // Request the desired hardware sample rate.
    self.graphSampleRate = 44100.0;    // Hertz

    [mySession setPreferredHardwareSampleRate: graphSampleRate
                                        error: &audioSessionError];

    if (audioSessionError != nil) {

        NSLog (@"Error setting preferred hardware sample rate.");
        return;
    }

    // Activate the audio session
    [mySession setActive: YES
                   error: &audioSessionError];

    if (audioSessionError != nil) {

        NSLog (@"Error activating audio session during initial setup.");
        return;
    }

    // Obtain the actual hardware sample rate and store it for later use in the audio processing graph.
    self.graphSampleRate = [mySession currentHardwareSampleRate];

    // Register the audio route change listener callback function with the audio session.
    AudioSessionAddPropertyListener (
        kAudioSessionProperty_AudioRouteChange,
        audioRouteChangeListenerCallback,
        self
    );
}

当使用音频单元播放声音时，您会在核心音频的哪一点说“通过扬声器播放”？

Answer 1

您可以使用setCategory withOption:

[mySession setCategory:AVAudioSessionCategoryPlayAndRecord withOptions:AVAudioSessionCategoryOptionDefaultToSpeaker error:&audioSessionError];