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我有一个获取请求如下：

NSFetchRequest *songRequest = [NSFetchRequest fetchRequestWithEntityName:@"Song"];

我还有一个名为genreFilter 的类型的NSSet (NSManagedObjects)。

我想设置一个谓词来过滤与genreFilter中的流派有关系的歌曲。

我可以以这种方式设置 NSPredicate 吗：

NSPredicate *songRequestPredicate = [NSPredicate predicateWithFormat:@"genre IN %@", [_genreFilter allObjects]];

?

流派如下所示：

@interface Genre : NSManagedObject

@property (nonatomic, strong) NSNumber * id;
@property (nonatomic, strong) NSString * name;
@property (nonatomic, strong) NSSet *preset;
@property (nonatomic, strong) NSSet *song;
@end
@interface Genre (CoreDataGeneratedAccessors)

- (void)addPresetObject:(Preset *)value;
- (void)removePresetObject:(Preset *)value;
- (void)addPreset:(NSSet *)values;
- (void)removePreset:(NSSet *)values;

- (void)addSongObject:(Song *)value;
- (void)removeSongObject:(Song *)value;
- (void)addSong:(NSSet *)values;
- (void)removeSong:(NSSet *)values;

@end

和这样的歌曲：

@interface Song : NSManagedObject

@property (nonatomic, strong) NSNumber * arousal;
@property (nonatomic, strong) NSNumber * id;
@property (nonatomic, strong) NSNumber * match;
@property (nonatomic, strong) NSNumber * popularity;
@property (nonatomic, strong) NSNumber * valence;
@property (nonatomic, strong) NSNumber * cloud;
@property (nonatomic, strong) Genre *genre;
@property (nonatomic, strong) Year *year;
@property (nonatomic, strong) Period *period;
@property (nonatomic, strong) NSNumber *yearReleased;

@property (nonatomic, assign) float score;
@property (nonatomic, readonly) MPMediaItem *mediaItem;

@end
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1 回答 1

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是的。这在我看来是正确的。

这是我对另一个问题的回答，它包含简单的说明和代码，可以让准系统核心数据项目启动并运行。我经常使用这个基本设置来快速测试这样的事情。

于 2012-10-18T09:00:25.863 回答