iOS GPUImage filters can't mix into video buffer

I'm working on a live app. I need to add filter into video buffer. Then I used GPUImage framework and write a filter. It looks well, but the buffer without any filter's effect in 'willOutputSampleBuffer:' function.

Here are some key code:

    self.videoCamera = [[GPUImageVideoCamera alloc] initWithSessionPreset:self.sessionPreset cameraPosition:AVCaptureDevicePositionFront];
    self.videoCamera.delegate = self;
    self.videoCamera.horizontallyMirrorFrontFacingCamera = YES;

    self.filterView = [[GPUImageView alloc] init];

    GPUImageBeautifyFilter *beautifyFilter = [[GPUImageBeautifyFilter alloc] init];
    [self.videoCamera addTarget:beautifyFilter];
    [beautifyFilter addTarget:self.filterView];


    dispatch_async(dispatch_get_main_queue(), ^{
        [self.view insertSubview:self.filterView atIndex:1];
        [self.filterView mas_makeConstraints:^(MASConstraintMaker *make) {
            make.edges.equalTo(self.view);
        }];
        [self.videoCamera startCameraCapture];
    });

Is there any detail I ignored? Thanks!!!

I need to add a new output to filter's target, so I add those code in my project, then I get the buffer with filter.

GPUImageRawDataOutput *rawDataOutput = [[GPUImageRawDataOutput alloc] initWithImageSize:CGSizeMake(720, 1280) resultsInBGRAFormat:YES];

[self.beautifyFilter addTarget:rawDataOutput];

__weak GPUImageRawDataOutput *weakOutput = rawDataOutput;

[rawDataOutput setNewFrameAvailableBlock:^{

    __strong GPUImageRawDataOutput *strongOutput = weakOutput;
    [strongOutput lockFramebufferForReading];
    GLubyte *outputBytes = [strongOutput rawBytesForImage];
    NSInteger bytesPerRow = [strongOutput bytesPerRowInOutput];
    CVPixelBufferRef pixelBuffer = NULL;
    CVPixelBufferCreateWithBytes(kCFAllocatorDefault, 720, 1280, kCVPixelFormatType_32BGRA, outputBytes, bytesPerRow, nil, nil, nil, &pixelBuffer);

    //Do something with pixelBuffer

    [strongOutput unlockFramebufferAfterReading];        
    CFRelease(pixelBuffer);

}];