AVAudioRecorder 录制完声音后 获取录音的时长

1、首先用音频文件路径创建一个URL

2、根据url创建 AVURLAsset
AVURLAsset *audioAsset = [AVURLAsset URLAssetWithURL:voiceURL options:nil];

3、取时长

 CMTime audioDuration = audioAsset.duration;
audioTime = CMTimeGetSeconds(audioDuration);