Swift 3 - 事件的监听

Swift 3之前 事件的监听很简单,直接"btnClick"就可以 ,但是这样存在一定的问题,以字符串的形式进行监听,如果字符串拼写错误,编译器是编译不出来的!

btn.addTarget(self, action: "sender", for: .touchUpInside)

所以Swift 3 苹果修复了这样的bug,采用#selector()进行事件的监听

btn.addTarget(self, action: #selector(btnClick), for: .touchUpInside)

Swift 3 按钮事件监听完整代码如下 :

import UIKit

class ViewController: UIViewController {
    
    var btn:UIButton = UIButton()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        btn.frame = CGRect(x: 0, y: 0, width: 100, height: 50)
        btn.center = view.center
        btn.setTitle("点我啊", for: .normal)
        btn.setTitle("上当了吧", for: .selected)
        btn.backgroundColor = UIColor.orange
        btn.addTarget(self, action: #selector(btnClick(sender:)), for: .touchUpInside)
        view.addSubview(btn)
        
        
    }
    
}

extension ViewController{
    
    @objc fileprivate func btnClick(sender : UIButton) {
        
        sender.isSelected = !sender.isSelected
        
    }
}