My first hackathon experience - 12 hours of hacking and building the essentials. https://medium.com/p/3db44088db70

1a-LiveCameraView.m

- (void)viewDidLoad {
    [super viewDidLoad];

    self.videoCamera = [[GPUImageVideoCamera alloc] initWithSessionPreset:AVCaptureSessionPreset640x480 cameraPosition:AVCaptureDevicePositionFront];
    self.videoCamera.outputImageOrientation = UIInterfaceOrientationPortrait;

    // self.avatarView is a non full screen GPUImageView instance
    // created in Storyboard
    [self.videoCamera addTarget:self.avatarView];
    [self.videoCamera startCameraCapture];
}

1b-BlurredBackground.m

self.blurFilter = ({
    GPUImageGaussianBlurFilter *blurFilter = [[GPUImageGaussianBlurFilter alloc] init];
    blurFilter.blurSize = 8;
    blurFilter;
});

self.videoCamera addTarget:self.blurFilter];

// self.blurView is a fullscreen GPUImageView instance configured in Storyboard
[self.blurFilter addTarget:self.blurView];

1c-MaskAvatar.m

self.avatarView.layer.cornerRadius = self.avatarView.frame.size.width/2;

2a-SlidingKeyboard.m

- (void)viewDidLoad {
    [super viewDidLoad];


    __weak typeof (self) weakSelf = self;
    [self.view addKeyboardPanningWithActionHandler:^(CGRect
keyboardFrameInView) {
      // Becareful of the retain cycle and use weakSelf instead of self
      // when you need to add custom logic in code.
      CGRect tableViewFrame = weakSelf.messageView.frame;
      tableViewFrame.size.height = toolBarFrame.origin.y;
      weakSelf.messageView.frame = tableViewFrame;
    }];
}

- (void)dealloc {
    [self.view removeKeyboardControl];
}