iOS传值－NSNotification

浏览数：30 / 时间：2015年06月11日

说明：通知在页面传值中，通知是非常简单便捷的方式，具体过程是，发布者发布通知到通知中心，订阅者从发布中心获得最新通知，具体结构如下图

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实现代码：

1，新建Single View Application工程，新建一个SecondViewController，用于作为发送端

2，在ViewController.m中添加UIButton用于跳转到SecondViewController，UILabel用于显示通知

@interface ViewController (){
    UILabel *_label;
}
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    //添加UIButton，用于跳转到SecondViewController
    UIButton *btn = [[UIButton alloc] initWithFrame:CGRectMake(20, 200, 300, 44)];
    [btn setTitle:@"ToSecondViewController" forState:UIControlStateNormal];
    btn.backgroundColor = [UIColor grayColor];
    [btn addTarget:self action:@selector(toSecondViewController) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:btn];
    
    //添加UILabel，用于显示SecondViewController传过来的值
    _label = [[UILabel alloc] initWithFrame:CGRectMake(20, 100, 300, 44)];
    _label.backgroundColor = [UIColor yellowColor];
    [self.view addSubview:_label];
    
}
- (void)toSecondViewController {
    SecondViewController *second = [[SecondViewController alloc] init];
    [self presentViewController:second animated:YES completion:nil];
}

3，在SecondViewController.m中添加UIButton，用于发送通知并且跳回ViewController，UILabel用于输入通知数据

@interface SecondViewController (){
    UITextField *_textField;
}

@end

@implementation SecondViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    //添加一个按钮用于返回ViewController
    UIButton *btn = [[UIButton alloc] initWithFrame:CGRectMake(20, 200, 300, 44)];
    [btn setTitle:@"BackToViewController" forState:UIControlStateNormal];
    btn.backgroundColor = [UIColor blueColor];
    [btn addTarget:self action:@selector(postNotification) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:btn];
    
    //添加一个UITextField
    _textField = [[UITextField alloc] initWithFrame:CGRectMake(20, 100, 300, 44)];
    _textField.backgroundColor = [UIColor greenColor];
    [self.view addSubview:_textField];
}

4，在SecondViewController.m中实现发送通知方法

- (void)postNotification {

    NSDictionary *dict = [[NSDictionary alloc] initWithObjectsAndKeys:_textField.text,@"test" ,nil];
    //创建通知
    NSNotification *notification =[NSNotification notificationWithName:@"getValue" object:nil userInfo:dict];
    //通过通知中心发送通知
    [[NSNotificationCenter defaultCenter] postNotification:notification];
    [self dismissViewControllerAnimated:YES completion:nil];

}

5，在ViewController.m中注册通知，并且实现注册通知方法

#import "ViewController.h"
#import "SecondViewController.h"

@interface ViewController (){
    UILabel *_label;
}
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    //添加UIButton，用于跳转到SecondViewController
    UIButton *btn = [[UIButton alloc] initWithFrame:CGRectMake(20, 200, 300, 44)];
    [btn setTitle:@"ToSecondViewController" forState:UIControlStateNormal];
    btn.backgroundColor = [UIColor grayColor];
    [btn addTarget:self action:@selector(toSecondViewController) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:btn];
    
    //添加UILabel，用于显示SecondViewController传过来的值
    _label = [[UILabel alloc] initWithFrame:CGRectMake(20, 100, 300, 44)];
    _label.backgroundColor = [UIColor yellowColor];
    [self.view addSubview:_label];
    
    
    //注册通知
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(getNotification:) name:@"getValue" object:nil];
    
}
- (void)toSecondViewController {
    SecondViewController *second = [[SecondViewController alloc] init];
    [self presentViewController:second animated:YES completion:nil];
}

//实现注册通知方法，给label赋值
-(void)getNotification:(NSNotification*)notification{

    NSDictionary *dict = [notification userInfo];
    _label.text = [dict objectForKey:@"test"];
    
}
@end