Question

I would know how to merge two array which contain some duplicate :
Here is an exemple to illustrate what I want to do :

// Here is some dictionary which contain an unique "id" key.
NSDictionary *dico1 = [NSDictionary dictionaryWithObjectsAndKeys:
                       @"11111111", @"id", nil];
NSDictionary *dico2 = [NSDictionary dictionaryWithObjectsAndKeys:
                       @"22222222", @"id", nil];
NSDictionary *dico3 = [NSDictionary dictionaryWithObjectsAndKeys:
                       @"33333333", @"id", nil];
NSDictionary *dico4 = [NSDictionary dictionaryWithObjectsAndKeys:
                       @"44444444", @"id", nil];
NSDictionary *dico5 = [NSDictionary dictionaryWithObjectsAndKeys:
                       @"55555555", @"id", nil];

// And here is duplicates of the 2nd and 3td dictionary.
NSDictionary *dico2_bis = [NSDictionary dictionaryWithObjectsAndKeys:
                           @"22222222", @"id", nil];
NSDictionary *dico3_bis = [NSDictionary dictionaryWithObjectsAndKeys:
                           @"33333333", @"id", nil];

And now I have an array which contain some of those dictionaries :

NSArray *currentArray = [NSArray arrayWithObjects:
                         dico1, dico2, dico3, nil];

And here is the new array to be merged with the first one which contain some duplicate and new “data” :

NSArray *tempArray = [NSArray arrayWithObjects:
                      dico2_bis, dico3_bis, dico4, dico5, nil];

My goal, at the final stage, is to have an array which contains all dictionaries with all duplicate deleted

NSArray *finalArray = [NSArray arrayWithObjects:
                       dico1, dico2, dico3, dico4, dico5, nil];

I don’t know how what is the most efficient solution, the merge do have to be fast. Do I have to implement a fast enumeration or a block based enumeration algorithm, or maybe a NSPredicate implementation ?.
I’ve already search about NSPredicate but I’ve not found a way to filter an array with an other array =/
Any help would be appreciated.

Answer 1

You do not use NSArrays, what you need is a set which automatically eliminates “duplicates” (a “doubloon” is a Spanish gold coin). So you are using simply an NSMutableSet and add your NSDictionaries to it.

NSMutableSet aSet = [NSMutableSet new];
[aSet addObject:dico1];
....