iOS Core Data 謂詞組合：使用 NSCompoundPredicate 實現 AND/OR 邏輯

問題背景

需構建查詢謂詞：(category 包含 cat0 OR cat1 OR cat2) AND (mark == 1)。

構建步驟

NSMutableArray *orPredicates = [NSMutableArray array];
if (cat0str.length) [orPredicates addObject:[NSPredicate predicateWithFormat:@"question.category CONTAINS[c] %@", cat0str]];
if (cat1str.length) [orPredicates addObject:[NSPredicate predicateWithFormat:@"question.category CONTAINS[c] %@", cat1str]];
if (cat2str.length) [orPredicates addObject:[NSPredicate predicateWithFormat:@"question.category CONTAINS[c] %@", cat2str]];

NSPredicate *compoundOr = [NSCompoundPredicate orPredicateWithSubpredicates:orPredicates];
NSPredicate *markPred = [NSPredicate predicateWithFormat:@"question.mark == 1"];

// 組合 AND
NSPredicate *finalPredicate = [NSCompoundPredicate andPredicateWithSubpredicates:@[compoundOr, markPred]];

[fetchRequest setPredicate:finalPredicate];

現代語法（Swift 風格）

NSPredicate *finalPredicate = [NSCompoundPredicate andPredicateWithSubpredicates:@[compoundOr, markPred]];

關鍵類

• NSCompoundPredicate：提供 andPredicateWithSubpredicates:、orPredicateWithSubpredicates:、notPredicateWithSubpredicate:
• 子謂詞數組順序不影響邏輯結果
• 可嵌套構建複雜邏輯：AND(OR(A,B), NOT(C))