MessagesViewController.swift

private func setupUI() {
    view.addSubview(cameraButton)
    cameraButton.translatesAutoresizingMaskIntoConstraints = false
    cameraButton.setImage(UIImage(systemName: "camera.fill",
                                    withConfiguration: UIImage.SymbolConfiguration(font: .systemFont(ofSize: 24))),
                            for: .normal)
    cameraButton.tintColor = UIColor.gray.withAlphaComponent(0.7)
    
    view.addSubview(soundRecordButton)
    soundRecordButton.translatesAutoresizingMaskIntoConstraints = false
    soundRecordButton.setImage(UIImage(systemName: "waveform.circle.fill",
                                        withConfiguration: UIImage.SymbolConfiguration(font: .systemFont(ofSize: 30, weight: .bold))),
                            for: .normal)
    soundRecordButton.tintColor = UIColor.gray.withAlphaComponent(0.7)
    
    NSLayoutConstraint.activate([
        cameraButton.centerYAnchor.constraint(equalTo: composerView.centerYAnchor),
        cameraButton.leftAnchor.constraint(equalTo: view.leftAnchor, constant: 16),
        cameraButton.heightAnchor.constraint(equalToConstant: 40),
        
        soundRecordButton.centerYAnchor.constraint(equalTo: composerView.centerYAnchor),
        soundRecordButton.rightAnchor.constraint(equalTo: composerView.rightAnchor, constant: -2),
    ])
    
    composerView
        .sendButtonVisibility
        .asDriver(onErrorJustReturn: (isHidden: false, isEnabled: false))
        .drive(onNext: { [weak self] state in
            self?.soundRecordButton.isHidden = !state.isHidden
        }).disposed(by: disposeBag)
}