macOS Mutable array for NSRect and similar types.

What are good options for storing types that aren't NSObjects in an array type structure with dynamic size?

I guess I could use NSMutableArray and box the types in objects for instance with the NSStringFromRect type functions, but that sounds like quite some overhead and I need this to go fast.

Edit: Found the answer:
Wrap each NSRect in an NSValue, and use an NSMutableArray as usual.