通知传值(NSNotificationCenter)

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通知传值

//流程:

1.注冊通知

2.通知中心,发送一条消息通知----------当中name名字千万不要写错了,会出如今3个地方

3.实现通知中心内部的方法,并实现传值

4.第四步,消息发送完,要移除掉

代码例如以下:

#import "FirstViewController.h"
#import "SecondViewController.h"
#import "UIButton+Create.h"
@interface FirstViewController ()
{
    UILabel * _label;
}
@end

@implementation FirstViewController
- (void)dealloc
{
    [_label release];
    //第四步,消息发送完,要移除掉
    [[NSNotificationCenter defaultCenter]removeObserver:self name:@"labelTextNotification" object:nil];
    [super dealloc];
}
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];

    self.view.backgroundColor = [UIColor redColor];
    self.navigationItem.title = @"首页";

    _label = [[UILabel alloc]initWithFrame:CGRectMake(50, 80, 200, 30)];
    _label.backgroundColor = [UIColor greenColor];
    [self.view addSubview:_label];

    UIButton * button = [UIButton systemButtonWithFrame:CGRectMake(100, 120, 50, 50) title:@"Push" target:self action:@selector(didClickButtonAction)];
    [self.view addSubview:button];

    //第二步,通知中心,发送一条消息通知----------当中name名字千万不要写错了,会出如今3个地方
    [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(showLabelText:) name:@"labelTextNotification" object:nil];

	// Do any additional setup after loading the view.
}

- (void)showLabelText:(NSNotification *)notification
{
    //第三,实现通知中心内部的方法,并实现传值
    id text = notification.object;
    _label.text = text;
}

- (void)didClickButtonAction
{

    SecondViewController * secondVC = [[SecondViewController alloc]init];
    [self.navigationController pushViewController:secondVC animated:YES];
    [secondVC release];
}

- (void)didClick:(NSString *)text
{
    _label.text = text;
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

#import "SecondViewController.h"
#import "FirstViewController.h"
#import "UIButton+Create.h"
@interface SecondViewController ()
{
    UITextField * _textField;//创建一个输入框
}
@end
@implementation SecondViewController

- (void)dealloc
{
    [_textField release];
    [super dealloc];
}
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor orangeColor];
    self.navigationItem.title = @"第二页";

    _textField = [[UITextField alloc]initWithFrame:CGRectMake(50, 80, 200, 30)];
    _textField.borderStyle = UITextBorderStyleRoundedRect;
    [self.view addSubview:_textField];

    UIButton * button = [UIButton systemButtonWithFrame:CGRectMake(100, 120, 50, 50) title:@"Back" target:self action:@selector(didClickButtonAction)];
    [self.view addSubview:button];

	// Do any additional setup after loading the view.
}

- (void)didClickButtonAction
{

    //第一步注冊通知
    [[NSNotificationCenter defaultCenter]postNotificationName:@"labelTextNotification" object:_textField.text];
    [self.navigationController popToRootViewControllerAnimated:YES];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

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