通知传值

#import <UIKit/UIKit.h>

@interface AppDelegate : UIResponder <UIApplicationDelegate>

@property (strong, nonatomic) UIWindow *window;

@end

/**
 * 通知在一对多的时候使用，从性能考虑一对一时不建议使用
 */

#import "AppDelegate.h"
#import "RootViewController.h"
@interface AppDelegate ()

@end

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    self.window.backgroundColor = [UIColor whiteColor];

    //初始化导航控制器
    UINavigationController *navi = [[UINavigationController alloc] initWithRootViewController:[[RootViewController alloc] init]];
    self.window.rootViewController = navi;

    [self.window makeKeyAndVisible];
    return YES;
}

@end

#import <UIKit/UIKit.h>

@interface RootViewController : UIViewController

@end

#import "RootViewController.h"
#import "LFViewController.h"
@interface RootViewController ()

@property(nonatomic, strong) UILabel *messageLabel ;

@end

@implementation RootViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    //添加按钮
    UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
    button.frame = CGRectMake(100, 100, 150, 60);
    [button setTitle:@"push到下一个页面" forState:0];
    [button setBackgroundColor:[UIColor greenColor]];
    [button addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:button];

    //添加Label
    self.messageLabel = [[UILabel alloc] initWithFrame:CGRectMake(100, 200, 150, 60)];
    self.messageLabel.backgroundColor = [UIColor greenColor];
    self.messageLabel.textAlignment = NSTextAlignmentCenter;
    [self.view addSubview:self.messageLabel];

    [self addNotification];
}

/**
 *  添加通知
 */
- (void)addNotification{
    /**
     *  @param receiveNotification: 接收通知后执行的方法
     *
     *  @name: 通知的名字
     */
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(receiveNotification:) name:@"notification" object:nil];
}
/**
 *  接收到通知
 */
- (void)receiveNotification:(NSNotification*)info{
    NSDictionary *dict = info.userInfo;
    NSString *message = dict[@"info"];
    if (message) {
        NSLog(@"%@",message);
        self.messageLabel.text = message;
    }
}

/**
 *  按钮事件
 */
- (void)buttonAction:(UIButton*)sender{
    LFViewController *lfController = [[LFViewController alloc] init];
    [self.navigationController pushViewController:lfController animated:YES];
}

-(void)dealloc{
    //移除通知
    [[NSNotificationCenter defaultCenter] removeObserver:self name:@"notification" object:nil];
}

@end

#import <UIKit/UIKit.h>

@interface LFViewController : UIViewController

@end

#import "LFViewController.h"

@interface LFViewController ()

@end

@implementation LFViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    //添加按钮
    UIButton *backBtn = [UIButton buttonWithType:UIButtonTypeCustom];
    backBtn.frame = CGRectMake(100, 100, 150, 60);
    [backBtn setTitle:@"返回且发送通知" forState:0];
    [backBtn setBackgroundColor:[UIColor greenColor]];
    [backBtn addTarget:self action:@selector(backBtnAction:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:backBtn];

}
/**
 *  backBtn按钮的事件
 */
- (void)backBtnAction:(UIButton*)sender{
    NSDictionary *dict = @{@"info":@"a good news"};
    /**
     * @Name      通知的名字
     * @userInfo  通知携带的信息
     */
    NSNotification *notification = [[NSNotification alloc] initWithName:@"notification" object:nil userInfo:dict];
    //发送通知
    [[NSNotificationCenter defaultCenter] postNotification:notification];
    [self.navigationController popViewControllerAnimated:YES];
}

@end