Swift学习笔记（五）：自定义视图

• 自定义视图
• 使用NSLayoutConstraint实现布局
• Block的使用，并防止循环引用
• 使用deinit代替OC中的delloc

class MyNavigationBar: UIView {

    //定义

    typealias BackBlock = ()->Void

    //声明

    var backBlock: BackBlock?

    

    var backButton = UIButton()

    var titleLabel = UILabel()

    

    override init(frame: CGRect) {

        super.init(frame: frame)

        setupView()

    }

    

    required init?(coder: NSCoder) {

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

    }

    

    func setupView() {

        backgroundColor = UIColor(colorHex: 0xEEEEEE)

        self.frame = CGRect(x: 0, y: 0, width: UIScreen.main.bounds.width, height: 88)

        

        self.addSubview(backButton)

        backButton.translatesAutoresizingMaskIntoConstraints = false

        backButton.bottomAnchor.constraint(equalTo: self.bottomAnchor).isActive = true

        backButton.leftAnchor.constraint(equalTo: self.leftAnchor, constant: 10).isActive = true

        backButton.widthAnchor.constraint(equalToConstant: 44).isActive = true

        backButton.heightAnchor.constraint(equalToConstant: 44).isActive = true

        

        self.addSubview(titleLabel)

        titleLabel.translatesAutoresizingMaskIntoConstraints = false

        titleLabel.centerXAnchor.constraint(equalTo: self.centerXAnchor).isActive = true

        titleLabel.bottomAnchor.constraint(equalTo: self.bottomAnchor).isActive = true

        titleLabel.heightAnchor.constraint(equalToConstant: 44).isActive = true

        

        backButton.setImage(UIImage(named: "navi_back_black"), for: .normal)

        backButton.addTarget(self, action: #selector(backAction), for: .touchUpInside)

        

        titleLabel.text = ""

        titleLabel.textColor = UIColor(colorHex: 0x333333)

        titleLabel.font = UIFont.boldSystemFont(ofSize: 18)

        titleLabel.textAlignment = .center

        

    }

    

    @objc func backAction() {

        self.backBlock?()

    }

    
}

class BaseViewController: UIViewController {


    var myNaviBar = MyNavigationBar()

 
    override func viewDidLoad() {

        super.viewDidLoad()

        
        view.backgroundColor = .white

        
        navigationController?.navigationBar.isHidden = true


        view.addSubview(myNaviBar)

        

        if navigationController?.viewControllers.count ?? 0 > 1 {

            weak var weakself = self

            myNaviBar.backBlock = {

                weakself?.navigationController?.popViewController(animated: true)

            }

        }

        else {

            myNaviBar.backButton.isHidden = true

        }

        

    }

    
    deinit {

        print("deinit - \(Self.self)")

    }

}