如何接收NSUserDefaultsDidChangeNotification iphone [英] How to receive NSUserDefaultsDidChangeNotification iphone

问题描述

经过大量搜索，我无法找到你需要传递字典对象的东西：

After a lot of searching I was not able to find wheather you need to pass a dictionary object to:

[NSUserDefaultsDidChangeNotification addObserver: forKeyPath: options: context:];

如果我想在userDefaults中进行一次更改通知我应该在选项中提供什么。还有什么是keypath？

and what should be provided in options if I want to be notified for even a single change in the userDefaults. Also what is keypath?

提前完成。

推荐答案

NSUserDefaultsDidChangeNotification 只是在更改默认值时发出的通知。要听取它，你需要这个代码：

NSUserDefaultsDidChangeNotification is just a notification that is sent out when the defaults are changed. To listen out for it you need this code :

    NSNotificationCenter *center = [NSNotificationCenter defaultCenter];
    [center addObserver:self
               selector:@selector(defaultsChanged:)  
                   name:NSUserDefaultsDidChangeNotification
                 object:nil];

这将调用方法defaultsChanged：触发通知时。你需要像这样实现这个方法：

This will call the method defaultsChanged: when the notification is fired. You need to implement this method like this :

- (void)defaultsChanged:(NSNotification *)notification {
    // Get the user defaults
    NSUserDefaults *defaults = (NSUserDefaults *)[notification object];

    // Do something with it
    NSLog(@"%@", [defaults objectForKey:@"nameOfThingIAmInterestedIn"]);
}

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