利用delegate實(shí)現(xiàn)兩個(gè)Controller之間的傳值

RootViewController中用個(gè)lable和一個(gè)按鈕内贮，點(diǎn)擊按鈕跳轉(zhuǎn)到模態(tài)窗口产园。在模態(tài)窗口中有個(gè)TextField和一個(gè)按鈕，輸入文字點(diǎn)擊關(guān)閉模態(tài)按鈕后跳轉(zhuǎn)到RootViewController夜郁，并改變其label為輸入的值什燕。

• AppDelegate.swift

//  AppDelegate.swift
   import UIKit
@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate{

  var window: UIWindow?

  func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
        self.window = UIWindow(frame: UIScreen.mainScreen().bounds)
        self.window?.backgroundColor = UIColor.darkGrayColor()
        self.window?.makeKeyAndVisible()
        let rootVc = RootViewController()
        self.window?.rootViewController = rootVc
        return true
    }

• RootViewController.swift

import UIKit
//實(shí)現(xiàn)ModeViewControlDelegate協(xié)議
class RootViewController: UIViewController,MdoeViewControlDelegate{
    var btn:UIButton?
    var label:UILabel?
    //實(shí)現(xiàn)協(xié)議中的方法
    func changeLabel(newString:String)  {
        self.label!.text = newString
    }
    func btnOnClick(){
        print("Onclick")
        
        let modeView = ModeViewController()
        //設(shè)置modeView中的代理為RootViewController自身
        modeView.delegate=self
        //跳轉(zhuǎn)到ModelView
        self.presentViewController(modeView,
                                   animated: true ,
                                   completion: {
                                    print("OK")
        })
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
self.view.backgroundColor = UIColor.grayColor()
        label = UILabel()
        label!.frame = CGRectMake(110, 40, 100, 20)
        label!.backgroundColor = UIColor.greenColor()
        label!.text = "你好！"
        label!.textAlignment = .Center
        
        btn = UIButton()
        btn!.frame = CGRectMake(110, 80, 100, 20)
        btn!.backgroundColor = UIColor.greenColor()
        btn!.setTitle("下一視圖", forState: .Normal)
        btn!.addTarget(self, action:#selector(RootViewController.btnOnClick), forControlEvents: .TouchUpInside)
        self.view.addSubview(label!)
        self.view.addSubview(btn!)
    }
 
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

}

• ModeViewControler.swift

import UIKit

class ModeViewController: UIViewController {
    var textF:UITextField?
    var delegate:MdoeViewControlDelegate?

    //點(diǎn)擊事件
    func btnOnClick(){
        let str = textF?.text
        print(str)
        
        // 調(diào)用代理函數(shù) 改變label值
        self.delegate?.changeLabel(str!)
        //返回RootView
        self.dismissViewControllerAnimated(true, completion: nil)
    }
    override func viewDidLoad() {
        super.viewDidLoad()
        
        view.backgroundColor=UIColor.cyanColor()
        
        
        textF=UITextField()
        textF!.frame=CGRectMake(110,40,100,20)
        textF!.backgroundColor=UIColor.greenColor()
        textF!.borderStyle = .RoundedRect
        
        
        let btn=UIButton(frame:CGRectMake(110,80,100,20))
        btn.backgroundColor=UIColor.greenColor()
        btn.setTitle("返回上視圖",forState:.Normal)
        //綁定事件
        btn.addTarget(self,action:#selector(ModeViewController.btnOnClick),forControlEvents: UIControlEvents.TouchUpInside)
        
        self.view.addSubview(btn)
        self.view.addSubview(textF!)
        
        
        // Do any additional setup after loading the view.
    }
}

• Protocol.swift

import Foundation
//協(xié)議定義要實(shí)現(xiàn)的方法
protocol MdoeViewControlDelegate {
    func changeLabel(neString:String)
}