当我使用 AVAssetWriterInput 时,readyForMoreMediaData 的值始终为 NO,但为什么呢?

when i use AVAssetWriterInput, the value of readyForMoreMediaData is always is NO, but why?

当我使用AVFoundation录制视频时,视频没有音轨,这段代码是怎么回事?readyForMoreMediaData的值一直是return没有,'appendSampleBuffer:'方法没有执行.. .??

1.
AVAssetWriterInput *audioWriterInput = [self audioWriterInput];
if ([self.assetWriter canAddInput:audioWriterInput]) {
    [self.assetWriter addInput:audioWriterInput];
}
2.
- (AVAssetWriterInput *)audioWriterInput {
    NSDictionary *audioCompressionSettings =
  @{
        AVEncoderBitRatePerChannelKey:@(28000),
        AVFormatIDKey : @(kAudioFormatMPEG4AAC),
        AVNumberOfChannelsKey : @(1),
        AVSampleRateKey : @(22050)
  };
    AVAssetWriterInput *audioWriterInput = [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeAudio outputSettings:audioCompressionSettings];
    audioWriterInput.expectsMediaDataInRealTime = YES;
    self.audioWriterInput = audioWriterInput;
    return audioWriterInput;
}
3.
- (void)appendingAudioSampleBuffer:(CMSampleBufferRef)sampleBuffer {
    // readyForMoreMediaData is always return NO
    if(self.audioWriterInput.readyForMoreMediaData) {
        BOOL success = [self.audioWriterInput appendSampleBuffer:sampleBuffer];
        if (success) {
            NSLog(@"");
        } else {

        }
    }
}

我真是个傻孩子。我用错了getter方法!!!