引言

闭包和协议传值一直是iOS App中开发中非常常见的使用，记录下，本人对闭包协议也不是很理解。还有的一种方法是通知，等忙完了再更新。

1. 通知

• 第一个控制器的内容是：

import UIKit

class TZViewController: UIViewController {
    var Label = UILabel()
    var btn = UIButton()
    override func viewDidLoad() {
        super.viewDidLoad()
        self.title = "通知"
        self.view.backgroundColor = UIColor.white
        configureUI()
        print("通知完毕")
        let notificationName = Notification.Name(rawValue: "DownloadImageNotification")
        // 注册通知
        NotificationCenter.default.addObserver(self,
                                               selector:#selector(downloadImage(notification:)),
                                               name: notificationName, object: nil)
    }
    func configureUI(){
        btn.frame = CGRect(x: 100, y: 300, width: kScreenwidth - 200, height: 44)
        btn.setTitle("确定", for: .normal)
        btn.setTitleColor(UIColor.black, for: .normal)
        btn.addTarget(self, action: Selector("BtnClick"), for: .touchUpInside)
        self.view.addSubview(btn)

        Label.frame = CGRect(x: 20, y: 64, width: kScreenwidth - 40, height: 44)
        Label.font = UIFont.systemFont(ofSize: 15)
        Label.text = "通知传值"
        Label.textColor = UIColor.black
        Label.textAlignment = .center
        self.view.addSubview(Label)
    }
    func downloadImage(notification: Notification){
        let userInfo = notification.userInfo as! [String: AnyObject]
        Label.text = "姓名: \(userInfo["name"] as! String),年龄: \(userInfo["age"] as! String) "
    }
    func BtnClick(){
        let vc = TZViewController1()
        self.navigationController?.pushViewController(vc, animated: true)
    }
    deinit {
        // 移除通知监听
        NotificationCenter.default.removeObserver(self)
    }
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
}

• 第二个控制器的内容是：

import UIKit

class TZViewController1: UIViewController {
    var btn = UIButton()
    override func viewDidLoad() {
        super.viewDidLoad()
        self.title = "传值"
        self.view.backgroundColor = UIColor.white
        configureUI()
        print("发送通知")
        let notificationName = Notification.Name(rawValue: "DownloadImageNotification")
        let dic = ["name": "zengen","age": "24"]
        // 发送通知
        NotificationCenter.default.post(name: notificationName, object: nil, userInfo: dic)
    }
    func configureUI(){
        btn.frame = CGRect(x: 100, y: 300, width: kScreenwidth - 200, height: 44)
        btn.setTitle("确定", for: .normal)
        btn.setTitleColor(UIColor.black, for: .normal)
        btn.addTarget(self, action: Selector("BtnClick"), for: .touchUpInside)
        self.view.addSubview(btn)
    }
    func BtnClick(){
        self.navigationController?.popViewController(animated: true)
    }
        override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
}

2. 协议的反向传值(一定在第一个控制器写代理，并且实现代理方法)

• 第一个控制器的内容：

import UIKit

class XYViewController: UIViewController{
    var btn = UIButton()
    override func viewDidLoad() {
        super.viewDidLoad()
        self.title = "协议"
        
        self.view.backgroundColor = UIColor.white
        configureUI()
        // Do any additional setup after loading the view.
    }
    func configureUI(){
        btn.frame = CGRect(x: 100, y: 300, width: kScreenwidth - 200, height: 44)
        btn.setTitle("确定", for: UIControlState.normal)
        btn.setTitleColor(UIColor.black, for:UIControlState.normal)
        btn.addTarget(self, action: "bClick", for: UIControlEvents.touchUpInside)
        self.view.addSubview(btn)
    }
    func bClick(){
        let vc = XYViewController1()
        vc.delegate_ze = self
        self.navigationController?.pushViewController(vc, animated: true)
    }
    
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
}
extension XYViewController: ZEdelegte{
    func change(title: String) {
        self.btn.setTitle(title, for: .normal)
    }
    func changeColor(Color: UIColor) {
        self.btn.setTitleColor(Color, for: .normal)
    }
}

• 第二个控制器的内容是：

import UIKit
//要创建一个协议
protocol ZEdelegte : NSObjectProtocol{
    //在协议里面，声明方法
    //  第一个，改变标题
    func change(title:String)
    //  第二个，改变颜色
    func changeColor(Color:UIColor)
}
class XYViewController1: UIViewController {
    //  创建一个准守协议的对象
    var delegate_ze :ZEdelegte?
    var btn = UIButton()
    override func viewDidLoad() {
        super.viewDidLoad()
        self.title = "传值"
        self.view.backgroundColor = UIColor.white
        configureUI()
    }
    func configureUI(){
        btn.frame = CGRect(x: 100, y: 300, width: kScreenwidth - 200, height: 44)
        btn.setTitle("返回", for: UIControlState.normal)
        btn.setTitleColor(UIColor.black, for:UIControlState.normal)
        btn.addTarget(self, action: "bClick", for: UIControlEvents.touchUpInside)
        self.view.addSubview(btn)
    }
    func bClick(){
        delegate_ze?.change(title: "zengen")
        delegate_ze?.changeColor(Color: UIColor.red)
        self.navigationController?.popViewController(animated: true)
    }
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
}

3. 闭包（Block）反向传值

• 第一个控制器的内容：

import UIKit

class BBViewController: UIViewController {
    let btn = UIButton()
    override func viewDidLoad() {
        super.viewDidLoad()
        self.title = "闭包"
        self.view.backgroundColor = UIColor.white
        configureUI()
    }
    func configureUI(){
        btn.frame = CGRect(x: 100, y: 300, width: kScreenwidth - 200, height: 44)
        btn.setTitle("确定", for: UIControlState.normal)
        btn.setTitleColor(UIColor.black, for:UIControlState.normal)
        btn.addTarget(self, action: "bClick", for: UIControlEvents.touchUpInside)
        self.view.addSubview(btn)
    }
    func bClick(){
        let vc = BBViewController1()
        vc.block = { (_ title:String, _ color:UIColor) in
            
            self.btn.setTitle(title, for: UIControlState.normal)
            self.btn.setTitleColor(color, for:UIControlState.normal)
        }
        self.navigationController?.pushViewController(vc, animated: true)
        
    }
    
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
}

• 第二个控制器是：

import UIKit

typealias valuesBlock = (_ title:String, _ color:UIColor)-> Void

class BBViewController1: UIViewController {
    
    var block: valuesBlock?
    let btn = UIButton()
    var text = UITextField()
    override func viewDidLoad() {
        super.viewDidLoad()
        self.title = "传值"
        self.view.backgroundColor = UIColor.white
        configureUI()
    }
    func configureUI(){
        text.frame = CGRect(x: 10, y: 200, width: kScreenwidth - 20, height: 44)
        text.placeholder = "输入文字"
        text.textAlignment = .left
        text.layer.borderWidth = 1
        text.layer.borderColor = UIColor.gray.cgColor //边框颜色
        text.layer.cornerRadius = 6.0
        text.font = UIFont.systemFont(ofSize: 15)
        self.view.addSubview(text)
        
        btn.frame = CGRect(x: 100, y: 300, width: kScreenwidth - 200, height: 44)
        btn.setTitle("返回", for: UIControlState.normal)
        btn.setTitleColor(UIColor.black, for:UIControlState.normal)
        btn.addTarget(self, action: "bClick", for: UIControlEvents.touchUpInside)
        self.view.addSubview(btn)
    }
    func bClick(){
        if text.text == ""{
            block!("zengen", UIColor.red)
        }
        else{
            block!(text.text!, UIColor.red)
        }
        self.navigationController?.popViewController(animated: true)
    }
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
}

• 最后附上github的demo地址：https://github.com/zengen1993/Notification