I Create custom button apple Sign up apple, error in here code:

private func setupSignUpWithAppleButton() {

        let signUpWithAppleButton: SignInAppleButton = SignInAppleButton()

        signUpWithAppleButton.addTarget(self, action: #selector(didTapSignUpWithAppleButton(_:)), for: .touchUpInside)

        subView.addSubview(signUpWithAppleButton)

        signUpWithAppleButton.fillInSuperview()

    }

This fixing code, with change addTarget to  tap Gesture 

  private func setupSignUpWithAppleButton() {

        let signUpWithAppleButton: SignInAppleButton = SignInAppleButton()

        subView.addSubview(signUpWithAppleButton)

        signUpWithAppleButton.fillInSuperview()

        let tapGesture = UITapGestureRecognizer(target: self, action: #selector(didTapSignUpWithAppleButton))

        signUpWithAppleButton.addGestureRecognizer(tapGesture)

    }

this full custom UIButton

public final class SignInAppleButton: UIButton {

    private lazy var containerView: UIView = {

        let view: UIView = UIView()

        view.translatesAutoresizingMaskIntoConstraints = false

        view.backgroundColor = .clear

        return view

    }()

    private lazy var appleLogoImageView: UIImageView = {

        let imageView: UIImageView = UIImageView()

        imageView.translatesAutoresizingMaskIntoConstraints = false

        imageView.image = UIImage(named: "appleLogo")?.withRenderingMode(.alwaysTemplate)

        imageView.tintColor = .white

        imageView.contentMode = .scaleAspectFit

        return imageView

    }()

    private lazy var textLabel: UILabel = {

        let label: UILabel = UILabel()

        label.translatesAutoresizingMaskIntoConstraints = false

        label.font = .systemFont(ofSize: 16, weight: .medium)

        label.textColor = .white

        return label

    }()

    public init() {

        super.init(frame: .zero)

        setupViews()

    }

    required init?(coder: NSCoder) {

        fatalError("init(coder:) has not been implemented")

    }

    private func setupViews() {

        backgroundColor = .black

        layer.cornerRadius = 6.0

        addSubview(containerView)

        containerView.addSubview(appleLogoImageView)

        containerView.addSubview(textLabel)

        NSLayoutConstraint.activate([

            containerView.topAnchor.constraint(equalTo: topAnchor),

            containerView.bottomAnchor.constraint(equalTo: bottomAnchor),

            containerView.centerXAnchor.constraint(equalTo: centerXAnchor),

            appleLogoImageView.topAnchor.constraint(equalTo: containerView.topAnchor),

            appleLogoImageView.leftAnchor.constraint(equalTo: containerView.leftAnchor),

            appleLogoImageView.bottomAnchor.constraint(equalTo: containerView.bottomAnchor),

            appleLogoImageView.widthAnchor.constraint(equalToConstant: 12),

            textLabel.topAnchor.constraint(equalTo: containerView.topAnchor),

            textLabel.leftAnchor.constraint(equalTo: appleLogoImageView.rightAnchor, constant: 6),

            textLabel.rightAnchor.constraint(equalTo: containerView.rightAnchor),

            textLabel.bottomAnchor.constraint(equalTo: containerView.bottomAnchor)

        ])

        textLabel.text = "Sign up with Apple"

        layoutIfNeeded()

    }

}