1 // 2 //  AppDelegate.h 3 //  delegatePassValue 4 // 5 //  Created by xiaoC on 16/9/28. 6 //  Copyright (c) 2016年 xiaoLeC. All rights reserved. 7 // 8  9 #import <UIKit/UIKit.h>10 11 @interface AppDelegate : UIResponder <UIApplicationDelegate>12 13 @property (strong, nonatomic) UIWindow *window;14 15 16 @end

 1 // 2 //  AppDelegate.m 3 //  delegatePassValue 4 // 5 //  Created by xiaoC on 16/9/28. 6 //  Copyright (c) 2016年 xiaoLeC. All rights reserved. 7 // 8  9 #import "AppDelegate.h"10 #import "ViewController.h"11 12 @interface AppDelegate ()13 14 @end15 16 @implementation AppDelegate17 18 19 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {20     // Override point for customization after application launch.21     22     self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];23     self.window.backgroundColor = [UIColor whiteColor];24     [self.window makeKeyAndVisible];25     self.window.rootViewController = [[ViewController alloc] init];26     27     28     return YES;29 }30 31 - (void)applicationWillResignActive:(UIApplication *)application {32     // Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.33     // Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.34 }35 36 - (void)applicationDidEnterBackground:(UIApplication *)application {37     // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.38     // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.39 }40 41 - (void)applicationWillEnterForeground:(UIApplication *)application {42     // Called as part of the transition from the background to the inactive state; here you can undo many of the changes made on entering the background.43 }44 45 - (void)applicationDidBecomeActive:(UIApplication *)application {46     // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.47 }48 49 - (void)applicationWillTerminate:(UIApplication *)application {50     // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.51 }52 53 @end

 1 // 2 //  ViewController.h 3 //  delegatePassValue 4 // 5 //  Created by xiaoC on 16/9/28. 6 //  Copyright (c) 2016年 xiaoLeC. All rights reserved. 7 // 8  9 #import <UIKit/UIKit.h>10 11 @interface ViewController : UIViewController12 13 14 @end

 1 // 2 //  ViewController.m 3 //  delegatePassValue 4 // 5 //  Created by xiaoC on 16/9/28. 6 //  Copyright (c) 2016年 xiaoLeC. All rights reserved. 7 // 8  9 #import "ViewController.h"10 #import "YFSecondViewController.h"11 12 13 @interface ViewController () <passValue> //1.遵守协议14 @property(nonatomic,strong)UILabel *lab;15 16 @end17 18 @implementation ViewController19 20 - (void)viewDidLoad {21     [super viewDidLoad];22     // Do any additional setup after loading the view, typically from a nib.23     self.view.backgroundColor = [UIColor grayColor];24     25     //添加一个跳转的按钮26     UIButton *jumpBtn = [UIButton buttonWithType:UIButtonTypeCustom];27     jumpBtn.frame = CGRectMake(100, 200, 200, 50);28     jumpBtn.backgroundColor = [UIColor yellowColor];29     [jumpBtn setTitle:@"跳转" forState:UIControlStateNormal];30     [jumpBtn setTitleColor:[UIColor grayColor] forState:UIControlStateNormal];31     [jumpBtn addTarget:self action:@selector(jump) forControlEvents:UIControlEventTouchUpInside];32     [self.view addSubview:jumpBtn];33     34     //创建一个label，接收传回来的值35     _lab = [[UILabel alloc] initWithFrame:CGRectMake(100, 400, 200, 50)];36     _lab.backgroundColor = [UIColor yellowColor];37     _lab.textAlignment = NSTextAlignmentCenter;38     [self.view addSubview:_lab];39     40 }41 42 //调用该方法跳转到YFSecondViewController控制器界面43 -(void)jump44 {45     YFSecondViewController *yfSecondV = [[YFSecondViewController alloc] init];46     //2.设置代理47     yfSecondV.delegate = self; //让ViewController控制器成为YFSecondViewController控制器的代理48     [self presentViewController:yfSecondV animated:YES completion:nil];49 }50 51 //3.实现协议方法52 -(void)backPassValue:(NSString *)str53 {54     //将返回来的值设置给label55     _lab.text = str;56 }57 58 59 @end

 1 // 2 //  YFSecondViewController.h 3 //   4 // 5 //  Created by xiaoC on 16/9/28. 6 // 7 // 8  9 #import <UIKit/UIKit.h>10 11 @protocol passValue <NSObject>12 13 -(void)backPassValue:(NSString *)str;14 15 @end16 17 @interface YFSecondViewController : UIViewController18 19 @property(nonatomic,weak) id <passValue> delegate;20 21 @end

 1 // 2 //  YFSecondViewController.m 3 //   4 // 5 //  Created by xiaoC on 16/9/28. 6 // 7 // 8  9 #import "YFSecondViewController.h"10 11 @interface YFSecondViewController ()12 13 @end14 15 @implementation YFSecondViewController16 17 - (void)viewDidLoad {18     [super viewDidLoad];19     self.view.backgroundColor = [UIColor orangeColor];20     21     //来一些数据22     NSArray *arr = @[@"深圳",@"上海",@"北京"];23     for (int i=0; i<3; i++) {24         UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];25         btn.frame = CGRectMake(100, (i*50)+80, 50, 40);26         [btn setTitle:arr[i] forState:UIControlStateNormal];27         [btn setTitleColor:[UIColor grayColor] forState:UIControlStateNormal];28         [btn addTarget:self action:@selector(back:) forControlEvents:UIControlEventTouchUpInside];29         [self.view addSubview:btn];30     }31     32     33 }34 35 -(void)back:(UIButton *)sender36 {37     //判断协议中的方法有没有实现，有实现就执行if中的语句38     if ([self.delegate respondsToSelector:@selector(backPassValue:)]) {39         40         [self.delegate backPassValue:sender.currentTitle];41         [self dismissViewControllerAnimated:YES completion:nil];42     }43 }44 45 - (void)didReceiveMemoryWarning {46     [super didReceiveMemoryWarning];47     // Dispose of any resources that can be recreated.48 }49 50 51 @end