Question

我对Objective-C比较陌生，但我之前用JavaScript解析过JSON。

我的viewDidLoad中有这段代码

NSURL *songsURL = [NSURL URLWithString:@"http://developer.echonest.com/api/v4/song/search?api_key=UVHRIOB9ISTKAAQ0R&format=json&results=1&combined=everybody%20dance%20now&bucket=id:7digital-UK&bucket=tracks&limit=true"];

NSData *jsonData = [NSData dataWithContentsOfURL:songsURL];

NSError *error = nil;

NSDictionary *dataDictionary = [NSJSONSerialization JSONObjectWithData:jsonData options:0 error:&error];

NSDictionary *item = [dataDictionary objectForKey:@"response"];
NSLog(@"%@", item);
NSDictionary *songs = [item objectForKey:@"songs"];
NSLog(@"%@", songs);
NSDictionary *songTitle = [songs objectForKey:@"title"];
NSLog(@"Title= %@", songTitle);

这一切都有效，直到我尝试获取歌曲标题。

获取歌曲后，JSON看起来像这样：

(
    {
    "artist_foreign_ids" =         (
                    {
            catalog = "7digital-UK";
            "foreign_id" = "7digital-UK:artist:2060042";
        }
    );
    "artist_id" = ARKSHFP12D5CD74F5D;
    "artist_name" = "Everybody Left";
    id = SOWGJIF143A016B701;
    title = "We Are Everybody Left";
    tracks =         (
                    {
            catalog = "7digital-UK";
            "foreign_id" = "7digital-UK:track:32612792";
            "foreign_release_id" = "7digital-UK:release:3062491";
            id = TRZNPMZ1429AA0B7CE;
            "preview_url" = "http://previews.7digital.com/clip/32612792";
            "release_image" = "http://artwork-    cdn.7static.com/static/img/sleeveart/00/030/624/0003062491_200.jpg";
        }
    );
 }
)

我尝试使用tracks获取其他值，例如NSDictionary *tracks = [songs objectForKey:@"tracks"];，但我仍然收到错误消息：

2014-08-29 01:54:07.612 khord[9530:60b] -[__NSCFArray objectForKey:]: unrecognized selector sent to     instance 0x987c450
2014-08-29 01:54:07.614 khord[9530:60b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFArray objectForKey:]: unrecognized selector sent to instance 0x987c450'

有谁能请我解决一下如何正确解析这个JSON。我有一种感觉，我没有正确理解数据类型。

Answer 1

歌曲是一系列词典，每个词典都有一个曲目键。

尝试：

[[songs objectAtIndex:0] valueForKey:@"tracks"]

使用Objective-C解析Echo Nest API JSON时出错

1 个答案: