Objective-C Mac OS X Distributed notifications iTu

问题:

i need a little help, i currently have a method; updateTrackInfo in my Mac OS X application which gets the artist name, the track name and duration of the track currently being played in iTunes

However i want the app to listen for the distributed iTunes notification; com.apple.iTunes.playerInfo then call the method updateTrackInfo when ever the notification is distributed by iTunes. Please could someone help me, on what i would need to write in both the header and implementation file.

Thanks, Sami.

回答1:

You're looking for -[NSDistributedNotificationCenter addObserver:selector:name:object:]:

NSDistributedNotificationCenter *dnc = [NSDistributedNotificationCenter defaultCenter];
[dnc addObserver:self selector:@selector(updateTrackInfo:) name:@"com.apple.iTunes.playerInfo" object:nil];

Elsewhere in the same class...

- (void) updateTrackInfo:(NSNotification *)notification {
  NSDictionary *information = [notification userInfo];
  NSLog(@"track information: %@", information);
}

It even gives you a whole bunch of track information in the notification. Isn't that nice?

回答2:

Thanks for your help, you helped me correct my code, I had this written up:

- (id) init {
self = [super init];
if (!self) return nil;
[[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(receiveNotification:) 
                                             name:@"com.apple.iTunes.playerInfo"
                                           object:nil];
return self;}

- (void) receiveNotification:(NSNotification *) notification {
if ([@"com.apple.iTunes.playerInfo" isEqualToString:@"com.apple.iTunes.playerInfo"]) {
    NSLog (@"Successfully received the test notification!");
}}

But it used NSNotificationCenter instead of NSDistributedNotificationCenter. Which is where I was going wrong.

Thanks, Sami.