为 NSNotification 注册 bool

发布于 2024-09-09 09:04:16 字数 680 浏览 2 评论 0原文

我试图将我的注意力集中在 NSNotification 上，但似乎无法让它工作。我认为我误解了如何注册通知。

我的连接管理器类中有一个 bool 作为属性。初始化时，我使用一些服务器进行身份验证，并检查是否可以访问外部 URL（应用程序主要用于公司内部网，外部连接并不总是可行）

如果无法访问，BOOL 属性将从 YES 更改为 NO连接，并且由于可以随时响应，因此我认为最好在其更改时注册通知。该属性称为 externalConnectionAvailable

[ConnectionManager addObserver:self forKeyPath:@"externalConnectionAvailable" options:(NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld) context:NULL];

并具有方法：

-(void) observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
    NSLog(@"observer called");
}

但这不会被调用。我做错了什么吗？

谢谢

原文

I'm trying to wrap my head around NSNotification but can't seem to get it to work. Think I'm misunderstanding how to register for an notification.

I have a bool as a property in my connection manager class. At initialisation I authenticate with a few servers and check if I can access an external URL (App will mainly be used on company intranet and an external connection isn't always possible)

The BOOL property will be changed from YES to NO if it cannot access the connection and as this can be responded at any time I thought it would be best to register a notification for when it changes. The property is called externalConnectionAvailable

[ConnectionManager addObserver:self forKeyPath:@"externalConnectionAvailable" options:(NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld) context:NULL];

and have the method:

-(void) observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
    NSLog(@"observer called");
}

But this doesn't get called. Am I doing something completely wrong?

Thanks

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開玄 2024-09-16 09:04:16

在这个声明中：

[ConnectionManager addObserver:self forKeyPath:@"externalConnectionAvailable" options:(NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld) context:NULL];

假设您遵循“Cocoa Way”并使用类和对象实例的常用命名方案，您似乎正在尝试为整个类（而不是对象实例）添加观察者。

你应该有类似的东西

ConnectionManager *connectionManagerInstance = // initialize manager...
...
[connectionManagerInstance addObserver:self forKeyPath:@"externalConnectionAvailable" options:(NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld) context:NULL];

In this statement:

[ConnectionManager addObserver:self forKeyPath:@"externalConnectionAvailable" options:(NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld) context:NULL];

Assuming that you are following the "Cocoa Way" and using the usual naming scheme for classes and object instances, you appear to be trying to add an observer for an entire class, as opposed to an object instance.

You should have something like

ConnectionManager *connectionManagerInstance = // initialize manager...
...
[connectionManagerInstance addObserver:self forKeyPath:@"externalConnectionAvailable" options:(NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld) context:NULL];

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