How to manage an Array of NSMutableArrays from same data source

This seems to be a basic problem that somehow got me stuck on the way to approach it. I'm trying to create 3 NSMutableArrays with a loop of 3 iterations. The NSMutableArrays contain the objects I need to work on. While the NSMutableArrays come from the same data source, their content differ in terms of data organization (or sequence) at each loop. The ideal would be to have an Array containing the 3 different NSMutableArrays. I tried therefore to create an helper to return a NSMutableArray at each loop. However, even if I assign the newly returned NSMutableArray to a specific variable (e.g. ArrayFirstLoop, ArraySecondLoop, etc.) through a switch statement, at each loop the previous Arrays are updated with the newly created Array from the latest loop (and this is not surprising given the pointer-nature of Arrays). What is then the right approach to what I am trying to do here? Thank you in advance.