swift4.0 方法监听Selector写法总结

import UIKit

class MainViewController: UITabBarController {

    //MARK:属性 懒加载
    lazy var composeBtn = UIButton(composeForeImageName: "tabbar_compose_icon_add", composeBackImageName: "tabbar_compose_button")

    //MARK:重写方法
    override func viewDidLoad() {
        super.viewDidLoad()
        tabBar.addSubview(composeBtn)
    }

    override func viewWillLayoutSubviews() {
        composeBtn.center = CGPoint(x: tabBar.center.x, y:tabBar.bounds.height * 0.5)

        //方法1：Selector("方法名")  Swift已经不推荐使用，会被提示改成第二种代替
//        composeBtn.addTarget(self, action:Selector(("composeBtnClick")), for: .touchUpInside)
        //方法2：Selector("类名.方法名") 推荐写法
        composeBtn.addTarget(self, action:#selector(MainViewController.composeBtnClick), for: .touchUpInside)
        //方法3："方法名"
//          composeBtn.addTarget(self, action:"composeBtnClick", for: .touchUpInside)

    }

}

//MARK:事件监听
extension MainViewController{

    //这里必须要加@objc 否则会崩溃
    @objc func composeBtnClick(){
        print("composeBtnClick")
    }
}