iOS NSNotificationCenter用于检查应用程序是否从后台到前台 [英] iOS NSNotificationCenter to check whether the app came from background to foreground

问题描述

我有一种情况，我必须每次从背景到前景初始化一个对象，并且应该使用NSNotificationCenter而不是appdelegate，因为我建立了一个静态库，因此不会有appdelegate，所以请帮助我同样。

I have a situation in which i have to intialize an object everytime when it comes from background to foreground and that should be using the NSNotificationCenter not with appdelegate because iam building a static library so there wont be appdelegate with that so please help me in the same.

推荐答案

你试过 UIApplicationWillEnterForegroundNotification ？

该应用程序还会在调用 applicationWillEnterForeground：之前不久发布UIApplicationWillEnterForegroundNotification通知，以便为感兴趣的对象提供响应转换的机会。

The app also posts a UIApplicationWillEnterForegroundNotification notification shortly before calling applicationWillEnterForeground: to give interested objects a chance to respond to the transition.

订阅通知：

[[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(yourUpdateMethodGoesHere:)
                                             name:UIApplicationWillEnterForegroundNotification
                                           object:nil];

实施需要调用的代码：

- (void) yourUpdateMethodGoesHere:(NSNotification *) note {
// code
}

不要忘记取消订阅：

[[NSNotificationCenter defaultCenter] removeObserver:self];

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