 <p>The <code>NSMutableSet</code> class declares the programmatic interface to an object that manages a mutable set of objects. <code>NSMutableSet</code> provides support for the mathematical concept of a set. </p> <p><code>NSMutableSet</code> is “toll-free bridged” with its Core Foundation counterpart, <code>CFMutableSetRef</code>.</p> <h3>Resources:</h3> <ul> <li><a href="http://www.gnustep.org/resources/OpenStepSpec/FoundationKit/Classes/NSMutableSet.html" rel="nofollow">gnustep</a> </li> <li><a href="https://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/nsmutableset_Class/Reference/NSMutableSet.html" rel="nofollow">NSMutableSet Class Reference</a></li> </ul>