Grouping of Custom Objects in Objective-C

Question

I have and array of custom objects of Person Class

Person : NSObject{
    NSString *firstName;
    NSString *lastName; 
    NSString *age;
}

NSMutableArray          


        

Answer 1

There isn't a built in group by method in NSArray. Your example implementation could be added as a category.

Unfortunately, the @distinctUnionOfObjects operation will only return the strings of the firstName property: John, David. It won't do a group by operation, nor is there such an operation.

Collection Operations