CoreData獲取請求 - 複雜謂詞

Question

我將如何使用（理想情況下）使用鍵值編碼集合運算符的單個謂詞來簡化此操作？ （感興趣到底該數組是filteredGames）

NSManagedObjectContext *context; 
NSFetchRequest *request = [[NSFetchRequest alloc] init]; 
[request setEntity:[NSEntityDescription entityForName:@"Game" inManagedObjectContext:context]; 
NSArray *games = [context executeFetchRequest:request error:nil]; 

NSMutableArray *filteredGames = [[NSMutableArray alloc] init]; 
for (Game *game in games) { 
    NSInteger maxRoundNumber = [game.rounds valueForKeyPath:@"@max.number"]; 
    Round *maxRound = [[game.rounds filteredSetUsingPredicate:[NSPredicate predicateWithFormat:@"number = %d", maxRoundNumber]] anyObject]; 
    if (maxRound.someBoolProperty) 
     [filteredGames addObject:game]; 
} 

遊戲有一個NSSet財產Roundsrounds，並Round有NSInteger財產number，和我在尋找那些Games，其最高數Round有一些BOOL財產someBoolProperty。

Answer 1

這似乎做你想要什麼：

NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Game"]; 
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"ANY SUBQUERY(rounds, $r, $r.someBoolProperty = YES).number = @max.rounds.number"];