以编程方式添加负约束

为什么我必须给我的 rigthAnchor titleLabel

private func setupLayout() {
    view.addSubview(imageView)
    view.addSubview(titleLabel)

    // *** imageView ***
    if #available(iOS 11.0, *) {
        imageView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 116).isActive = true
    } else {
        imageView.topAnchor.constraint(equalTo: view.topAnchor, constant: 116).isActive = true
    }
    imageView.rightAnchor.constraint(equalTo: view.rightAnchor).isActive = true
    imageView.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
    imageView.heightAnchor.constraint(equalToConstant: 224).isActive = true

    // *** titleLabel ***
    titleLabel.topAnchor.constraint(equalTo: imageView.bottomAnchor, constant: 25).isActive = true
    titleLabel.rightAnchor.constraint(equalTo: view.rightAnchor, constant: -28).isActive = true
    titleLabel.leftAnchor.constraint(equalTo: view.leftAnchor, constant: 28).isActive = true
}