I have the following 2 arrays. Array A with i.e. 10 id's, and the other array, Array B with 300 id's with all the corresponding data.
I want to retrieve all the data from B with id's which are stated in the array A.
I could just loop all entries in array B on every entry in array A, but this looks a little bit heavy for such simple task. What would be the best solutions in this case?
Thnx!
If you don't need an ordered array you could switch to an hash table (eg. NSSet) which has a much faster lookup time (strong bias towards O(1)). Otherwise you had to loop through the whole array and check all of its members.
Probably use a predicate (a, b are your arrays):
NSPredicate* filter = [NSPredicate predicateWithFormat: @"self IN %@", a];
NSArray* result = [b filteredArrayUsingPredicate: filter];
Although, it might only work if the objects in your arrays are simple things like strings.
When you are filling array B you can instead make it a dictionary. Assuming ids are unique you can then get value of the object for key in array A from array B. This will avoid looping and is sort of equivalent to hash table.
The returned value will then have the corresponding data for the particular unique id.
I don't see how you are going to do it otherwise if you are using arrays. The only way to access the right element is by looping through the array.
