I have an iPhone with about 6GB of messages. I'd like to get them off of my phone, but it would be nice if I could save a copy of them on my computer. Is there a way that iOS messages can be transferred to the MacOS Messages app?
No simple method. You can back up the phone to iTunes, and use one of the 3rd party "Backup Extractor" apps to pull the messages out of the backup and save them somewhere.