AVAudioSession的PlayAndRecord类和AVAudioSessionModeMeasurement与defaultToSpeaker选项不兼容？

Question

尝试使用AVAudioSessionModeMeasurement模式将AVAudioSession放入.playAndRecord类别会导致忽略.defaultToSpeaker选项，从而导致输出被安静地播放到耳机（也称为接收器）之外。

Answer 1

While there doesn't seem to be much written about this the documentation makes this "end result of audio output being sent to the receiver rather than speaker" seem like possible intended behavior and not a bug.

let AVAudioSessionModeMeasurement: String

This mode is intended for apps that need to minimize the amount of system-supplied signal processing to input and output signals. If recording on devices with more than one built-in microphone, the primary microphone is used.