Iphone 打印键的唯一值

我有一系列这样的格言：

    {
    "album_image" = "BauerOVTDDVD.jpg";
    "album_title" = "Zuid-Afrika, Om Van Te Dromen";
    "album_year" = 2005;
    "track_duration" = xxx;
    "track_title" = "Ik Neem Voor Jou De Laatste Trein";
},
    {
    "album_image" = "BauerOVTDDVD.jpg";
    "album_title" = "Zuid-Afrika, Om Van Te Dromen";
    "album_year" = 2005;
    "track_duration" = xxx;
    "track_title" = "Als De Avond Voor Ons Is Gevallen";
},
    {
    "album_image" = "BauerOVTDDVD.jpg";
    "album_title" = "Zuid-Afrika, Om Van Te Dromen";
    "album_year" = 2005;
    "track_duration" = "3'26";
    "track_title" = "'n Handje Vol Geluk";
},
    {
    "album_image" = "BauerOVTDDVD.jpg";
    "album_title" = "Zuid-Afrika, Om Van Te Dromen";
    "album_year" = 2005;
    "track_duration" = "3'22";
    "track_title" = "'n Klein Sterretje";
}

---

因此，每个曲目标题都有不同的曲目标题。其中一些曲目标题共享一张专辑。我只想打印独特的专辑标题。这是我必须处理的数据。我是否应该创建一个只包含专辑标题的新dict？

如果您只需要专辑标题，可以使用NSSet

NSMutableSet *titles = [NSMutableSet alloc] init];
[trackArray enumerateObjectsUsingBlock:^(id object, NSUInteger idx, BOOL *stop) {
   [titles addObject:[object objectForKey:@"album_title"]];
}];
[titles release];

---

您可以创建一组相册标题：

NSArray *albumTitlesWithDuplicates = [sourceArray valueForKey:@"album_title"];
NSSet *uniqueAlbumTitles = [NSSet setWithArray:albumTitlesWithDuplicates];