////  ViewController.swift//  DelegateDemo////  Created by Jason on 1/8/18.//  Copyright © 2018年 ET. All rights reserved.//import UIKitclass ViewController: UIViewController,ReturnValueDelegate {    @IBOutlet weak var resultLabel: UILabel!    override func viewDidLoad() {        super.viewDidLoad()    }    @IBAction func jumpSecond(_ sender: Any) {        let secondVC = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "secondViewController") as! SecondViewController        secondVC.delegate = self        secondVC.backClosure = {(message: String) in            print("闭包返回的值:\(message)")        }        self.navigationController?.pushViewController(secondVC, animated: true)    }        func returnMessage(message: String) {        print("代理返回的值:\(message)")        resultLabel.text = message    }}复制代码

////  SecondViewController.swift//  DelegateDemo////  Created by Jason on 1/8/18.//  Copyright © 2018年 ET. All rights reserved.//import UIKit//闭包返回值typealias InputClosure = (String) -> Void//定义协议只有class级别的才能集成代理protocol ReturnValueDelegate:class {    func returnMessage(message:String)}class SecondViewController: UIViewController {        @IBOutlet weak var textField: UITextField!    weak var delegate:ReturnValueDelegate?    var backClosure:InputClosure?        @IBAction func backAction(_ sender: Any) {        if (self.delegate != nil){            delegate?.returnMessage(message: textField.text!)            self.backClosure!(textField.text!)           self.navigationController?.popViewController(animated: true)        }    }}复制代码