从另一个视图更新文本标签

Question

我有一个NSTimer每10秒运行一次,并从LandingController.m开始.当您转到应用程序中的其他视图时,它将继续运行.我希望能够(当在该计时器内满足某个条件时)从另一个视图更新标签字段GuardMenu.m我想要更新的标签名为CurrentZone.text,我想将它从值"N"更新为值"Y".

这是我在LandingController.m上的计时器

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

在LandingController.m上调用它

- (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"

        }


    }

Answer 1

首先在initGuardMenu类的方法中创建一个NSNotification

- (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,这是您将更改CurrentZone标签文本的位置.

- (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方法中

启动计时器.

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

现在实现@selectorNSTimer,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:在NotificationName应该是相同的.

示例项目代码Dropbox Link