How to Ignore silence in audio buffer “background noise reduction” - iOS Chromatic Tuner? Ask

This is simple chromatic tuner for iOS (xCode). I want to make "ambient noise reduction", to ignore silence or low volume packets in audio buffer. Now they are not ignored and tuner gets crazy with random audio packages, I want tuner to work only when there is a valid sound not noise.

- (instancetype)initWithPitchTrackingHandler:(void (^)(NSNumber *pitch))pitchHandler {
    if (self = [super init]) {
        self.pitchUpdateHandler = pitchHandler;
        [self setupRemoteIO];
        dywapitch_inittracking(&_tracker);
    }
    return self;
}
- (void) dealloc {
/
}
- (void) processAudio:(AudioBufferList*)bufferList {
   
    /
    if (!self.buffer) {
        self.buffer = [NSMutableData dataWithBytes:bufferList->mBuffers[0].mData
                                            length:bufferList->mBuffers[0].mDataByteSize];
    } else {
        [self.buffer appendBytes:bufferList->mBuffers[0].mData
                          length:bufferList->mBuffers[0].mDataByteSize];
    }
   
    /
    int numberOfSamples = self.buffer.length/kBytesPerSample;
    if (numberOfSamples >= kSamplesNeeded) {
       
        /
        float *samplesAsFloat = (float *)self.buffer.mutableBytes;
        double *samplesAsDouble = (double *)malloc(numberOfSamples * sizeof(double));
        for (int i = 0; i < numberOfSamples; i++) {
            samplesAsDouble[i] = (double)samplesAsFloat[i];
        }
   
        /
        double pitch = dywapitch_computepitch(&_tracker, samplesAsDouble, 0, numberOfSamples);
       
        if (self.pitchUpdateHandler && pitch != 0.0) {
           
            dispatch_async(dispatch_get_main_queue(), ^{
                self.pitchUpdateHandler(@(pitch));
            });
        }
        /
        self.buffer = nil;
    }
}
@end