Question

我想在UINavigationController的酒吧展示一个现在的游乐纽。

我有一个班子(NowPlayingManager),我正在利用这个班子来跟踪一个声音档案是否正在发挥作用。我使用另一班(AudioViewController)上张贴的通知来表明竞争状况。录音记录员对现在PlayingManager的节目和节目进行播放。在目前PlayingManager, 收到通知的目标,我向YES投了通知。

当音频站起作用时,我又向NowPlaying bool发送了通知。

However, each time the class is initialized the bool is set to NO, which makes sense because it is a new instance of NowPlayingManager and the Now Playing button is never displayed.

How can I get the isNowPlaying bool to persist through all instances of my NowPlayingManager? Or, rather, Should I have the app delegate init the NowPlayingManager rather than AudioViewController so that only one instance is created?

Answer 1

You can of course define the isNowPlaying as class member + (BOOL) isNowPlaying. See Objective-C: how to declare a static member that is visible to subclasses? for more information on this.

But as you said already it seems to be more useful to create just one instance i.e. the singleton pattern. I suggest Matt Galaghers posting about singletons and his downloadable SynthesizeSingleton.h:

http://cocoawithlove.com/2008/11/singletons-appdelegates-and-top-level.html

Answer 2

If I understand correctly, you should use NSUserDefaults. This remembers it even if you change class, close the app, etc.

[[NSUserDefaults standardUserDefaults] setBool:YES forKey:@"KeyName"];

之后,将 b子检查成:

if ([[NSUserDefaults standardUserDefaults] boolForKey:@"KeyName"] == YES]

{

    //Do whatever you would do when the bool is equal to YES

}

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