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")
}
}