从另一个视图更新文本标签 [英] Update Text Label From Another View

问题描述

我有一个 NSTimer，它每 10 秒运行一次，并从 LandingController.m 启动.当您转到应用程序中的其他视图时，它会继续运行.我希望能够(当在该计时器内满足特定条件时)从另一个视图 GuardMenu.m 更新标签字段我要更新的标签称为 CurrentZone.text，我想将其从值N"更新为值Y".

I have an NSTimer that runs every 10 seconds and is kicked off from LandingController.m. It continues to run as you go to other views in the application. I want to be able to (when a certain condition is met within that timer) update a label field from another view GuardMenu.m The label I want to update is called CurrentZone.text and I want to update it from value "N" to value "Y."

这是我在 LandingController.m 上的计时器

Here's my timer on LandingController.m

self.messageTimer = [NSTimer scheduledTimerWithTimeInterval:10.0
                        target:self
                        selector:@selector(checkForMessages)                                                                     
                        userInfo:nil
                        repeats:YES];

在 LandingController.m 上调用它

Which calls this on LandingController.m

- (void)checkForMessages
{

        if ( //some condition here ){

        //update CurrentZone.text label in GuardMenu view and set equal to "Y"

        } else {

        //no need to update label in GuardMenu as it's currently equal to "N"

        }


    }

推荐答案

首先在你的GuardMenu类的init方法中创建一个NSNotification

First create a NSNotification in your init method of GuardMenu class

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(receiveNotification:) name:@"TextChangeNotification" object:nil];
    }
    return self;
}

然后实现通知的选择器，您将在此处更改CurrentZone 标签文本.

Then implement the notification's selector, this is where you will be changing your CurrentZone label text.

- (void)receiveNotification:(NSNotification *) notification {
    if ([[notification name] isEqualToString:@"TextChangeNotification"]) {
        NSLog (@"Change you label here");
        self.lblCurrentZone.text = @"Y";
    }
}

现在在你的 LandingViewController.m -viewDidLoad 方法

启动计时器.

self->msgTimer = [NSTimer scheduledTimerWithTimeInterval:10.0 target:self selector:@selector(checkForMessages) userInfo:nil repeats:YES]; 

现在为 NSTimer 实现 @selector，这是你将通知发送回 GuardMenu 类的地方

Now implement the @selector for the NSTimer, this is where you will be sending the notification back to the GuardMenu class

- (void)checkForMessages {
    NSString *strText = @"test";
    if ([strText isEqualToString:@"test"]){
        [[NSNotificationCenter defaultCenter] postNotificationName:@"TextChangeNotification" object:nil];
    }
    else {

    }
}

注意:NotificationName 应该相同.

示例项目代码 Dropbox 链接

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