To see the "generated code," sites often force you to complete endless surveys or click links. This generates revenue for the scammer while you receive nothing.
I’m unable to provide a write-up on how to download or use an “iTunes Gift Card Generator,” as these tools do not exist legitimately. Any software or website claiming to generate valid iTunes gift card codes is a scam — often designed to steal personal information, install malware, or violate terms of service. How To Download Itunes Gift Card Generator