IOS中Notificaiton通知的使用方法<代码演示>

最新推荐文章于 2019-09-04 15:49:46 发布

GFanStudio-LeeSir

最新推荐文章于 2019-09-04 15:49:46 发布

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分类专栏： IOS单例写法

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本文介绍如何在iOS应用中利用通知（NSNotification）进行消息传递，并通过ModalViewController展示通知的效果。通过实例展示了通知在不同视图间传递参数的方法，以及如何在ModalViewController中响应并使用接收到的通知来改变标签文本。

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//使用通知进行消息传递（通知NSNotificationCenter不可都用）
    //NSNotificationCenter可以在毫无关系的视图中进行参数传值
    //NSNotificationCenter是一个one-to-one &one-to-many &one-to- none的关系
    //过多使用会降低代码的可读性，增加程序的耦合度

- (void)viewDidLoad
{
    [super viewDidLoad];
// Do any additional setup after loading the view.
    self.view.backgroundColor = [UIColor purpleColor];

    //实例化一个用于显示的Label
    UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(50, 64, 100, 60)];
    label.text = @"没变化";
    label.backgroundColor = [UIColor whiteColor];
    label.tag = 100;
    [self.view addSubview:label];
    RELEASE_SAFETY(label);

    //实例化一个触发事件按钮
    UIButton *presentButton = [UIButton buttonWithType:UIButtonTypeRoundedRect ];
    presentButton.backgroundColor = [UIColor whiteColor];
    presentButton.frame = CGRectMake(50, 200, 200, 60);
    [presentButton setTitle:@"ModalViewController" forState:UIControlStateNormal];
    [presentButton addTarget:self

action:@selector(presetAction)

forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:presentButton];
    //使用通知进行消息传递（通知NSNotificationCenter不可都用）
    //NSNotificationCenter可以在毫无关系的视图中进行参数传值
    //NSNotificationCenter是一个one-to-one &one-to-many &one-to- none的关系
    //过多使用会降低代码的可读性，增加程序的耦合度
    //#define kChangeLabelValueByNotification @"kChangeLabelValueByNotification"宏定义
    [[NSNotificationCenter defaultCenter] addObserver:self

selector:@selector(changeLabelText:)

name:kChangeLabelValueByNotification

object:nil];


}
#pragma mark==实现通知方法=
-(void)changeLabelText:(NSNotification *)notification{

    //获取通知传递过来的对象
    id label = notification.object;
    //修改原有Label值
    ((UILabel *)[self.view viewWithTag:100]).text = label;

}
//实现模态方法
-(void)presetAction{

    ModalViewController *modal = [[ModalViewController alloc] init];
    [self presentViewController:modal animated:YES completion:nil];
    RELEASE_SAFETY(modal);

}
//重写析构函数
-(void)dealloc{

[[NSNotificationCenter defaultCenter] removeObserver:self

name:kChangeLabelValueByNotification

object:nil];
[super dealloc];
}

//ModalViewController.
- (void)viewDidLoad
{
    [super viewDidLoad];
// Do any additional setup after loading the view.
    self.view.backgroundColor = [UIColor purpleColor];
    //实例化一个用于显示的Label
    self.textField = [[[UITextField alloc] initWithFrame:CGRectMake(50, 64, 100, 60)] autorelease];
    self.textField.backgroundColor = [UIColor whiteColor];
    self.textField.borderStyle = UITextBorderStyleRoundedRect;
    [self.view addSubview:self.textField];

    //实例化一个触发事件按钮
    UIButton *dismissButton = [UIButton buttonWithType:UIButtonTypeRoundedRect ];
    dismissButton.backgroundColor = [UIColor whiteColor];
    dismissButton.frame = CGRectMake(50, 200, 200, 60);
    [dismissButton setTitle:@"dismissViewController" forState:UIControlStateNormal];
    [dismissButton addTarget:self

action:@selector(dismissAction)

forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:dismissButton];

}
-(void)dismissAction{

    [[NSNotificationCenter defaultCenter] postNotificationName:kChangeLabelValueByNotification

object:self.textField.text];

    [self dismissViewControllerAnimated:YES completion:nil];

}

-(void)dealloc{
    RELEASE_SAFETY(_textField);
    [super dealloc];
}