iphone - 及其安靜混淆使用塊來獲得從陣列

Question

我有對象（JSON對象）的陣列的子陣列 每個對象是以下的性質：

{ 
     author = "<null>"; 
     category =   { 
      "created_at" = "2011-02-06T18:11:39Z"; 
      id = 4; 
      name = lawyers; 
     }; 
     "created_at" = "<null>"; 
     id = 693; 
     "mobile_user_id" = "<null>"; 
     "rating_count" = 0; 
     status = 1; 
     text = "A brain walks into a bar and says, \"I'll have a pint of beer please. \"The barman looks at him and says \"Sorry, I can't serve you.\" \"Why not?\" asks the brain. \"You're already out of your head.\""; 
     title = "A brain goes to a local bar"; 
    } 

從對象的那些陣列，我想查找類別爲id = 4的對象並創建一個子數組。

有人可以幫我使用塊並從數組中獲取子數組嗎？

Answer 1

我想通過「使用塊」，你的意思是使用的NSArray的方法類似

- (NSIndexSet *)indexesOfObjectsPassingTest:(BOOL (^)(id obj, NSUInteger idx, BOOL *stop))predicate 

然後，它看起來像

NSIndexSet *indexes = [yourArray indexesOfObjectsPassingTest:^(id obj, NSUInteger idx, BOOL *stop) { 
    return (BOOL)([[obj valueForKeyPath:@"category.id"] intValue] == 4); 
}]; 
NSArray *filteredArray = [yourArray objectsAtIndexes:indexes]; 

這對你的要求，但我寧願使用filteredArrayUsingPredicate:像這樣：

NSPredicate *pred = [NSPredicate predicateWithFormat:@"category.id = %@", [NSNumber numberWithInt:4]]; 
NSArray *filteredArray = [yourArray filteredArrayUsingPredicate:pred];