How to produce bar codes from a Cocoa App ?

I need to produce bar codes : do you know of any bar code library available for Cocoa ?
Here are some references found on the Web:
Reference site regarding bar code:
Barcode-1

Shareware, freeware and commercial products:
Barcode Generator (source code available)
Barcode Producer 1.2.5
Swordfish
BarcodeX