通过不同视图的按钮更新标签 [英] Update a label through button from different view

问题描述

当它们都在不同类的 uiview 控制器中时如何通过按钮单击更新标签...单击按钮时，标签应该更新...我尝试了很多次..但它没有发生..

How to update a label by button clicks when they both are in different classes of uiview controller...when button is clicked,the label should be update...i tried many times..but its not happening..

还有一个问题是我的应用在模拟器中运行良好，但是当我在设备上运行时，动态创建的按钮(按钮图像)不可见，动作正在执行但图像丢失..我知道为什么吗?

one more Question is my app is running good in simulator but when i run on device the dynamically created button(button image) is not visible,action is performing but image is missing..may i know why?

推荐答案

有几种方法可以在 iOS 中保持视图(实际上是视图控制器)之间的通信.对我来说最简单的是发送通知.您在要进行更改的视图中为通知添加观察者，然后从将触发更改的视图中发布通知.这样你就可以从 ViewController B 告诉 ViewController A 东西准备好了，做出改变"

There are a few ways to maintain communication between views (view controllers, actually) in iOS. Easiest of which for me is sending notifications. You add an observer for a notification in the view you want to make the change, and from the view that will trigger the change, you post the notification. This way you tell from ViewController B to ViewController A that "something is ready, make the change"

当然，这需要您创建接收器视图并且已经在监听通知.

This, of course, requires your receiver view to be created and already be listening for the notification.

在 ViewController B(发送者)中

In ViewController B (sender)

- (void)yourButtonAction:(id)sender
{
    [[NSNotificationCenter defaultCenter] postNotificationName:@"theChange" object:nil];
}

在 ViewController A (receiver)添加观察者来监听通知:

In ViewController A (receiver) Add the observer to listen for the notification:

- (void)viewDidLoad
{
    //.........
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(makeTheChange) name:@"theChange" object:nil];
}

不要忘记删除它(在这种情况下，在 dealloc 上)

Do NOT forget to remove it (in this case, on dealloc)

- (void)dealloc
{
     [[NSNotificationCenter defaultCenter] removeObserver:self name:@"theChange" object:nil];
     [super dealloc];
}

最后，更新标签的方法

- (void)makeTheChange
{
    yourLabel.text = @"your new text";
}

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