 <p>The answer to your question is that Objective-C does not have a direct equivalent of annotations as found in Java/C#, and though as some have suggested you might be able to engineer something along the same lines it probably is either far too much work or won't pass muster.</p> <p>To address your particular need see <a href="http://stackoverflow.com/questions/5197446/nsmutablearray-force-the-array-to-hold-specific-object-type-only/5198040#5198040">this answer</a> which shows how to construct an array which holds objects of only one type; enforcement is dynamic and not static as with parametric types/generics, but that is what you'd be getting with your annotation so it probably matches your particular need in this case. HTH.</p>