1、左侧图标+文字

private lazy var backButton: UIButton = {
let button = UIButton()
button.setImage(ImageLoader.image(named: "back"), for: .normal)
button.imageView?.contentMode = .scaleAspectFit
button.imageEdgeInsets = UIEdgeInsets(top: 0, left: 8, bottom: 0, right: 0)
button.titleEdgeInsets = UIEdgeInsets(top: 0, left: 16, bottom: 0, right: -16)
button.setTitle(NSLocalizedString("SETTINGS", comment: ""), for: .normal)
button.addTarget(self, action: #selector(backOnTapped), for: .touchUpInside)
button.setTitleColor(.mainTextColor, for: .normal)
button.titleLabel?.font = UIFont.systemFont(ofSize: 18.0)
return button
}()
2、左侧返回图标,标题居中

public override func viewDidLoad() {
...
navigationItem.titleView = titleView
navigationController?.navigationBar.topItem?.backBarButtonItem = UIBarButtonItem(title: "", style: .plain, target: nil, action: nil)
...
}
private lazy var titleView: UILabel = {
let label = UILabel()
label.text = NSLocalizedString("Add Friend", comment: "Add friend")
label.textColor = .mainTextColor
label.font = .systemFont(ofSize: 18.0)
return label
}()