This question already has an answer here:
So I have a long conversation on my iPhone in the iMessages app. It is a long text message conversation with a friend. Now I want a copy of the whole conversation so I can send to another friend.
Right now I do: take a screen shot of every block of the conversation and send to my friend ⇒ 20 screenshots. Not practical for me and my recipient.
I know you can have iMessages in your MAC by using your Apple ID but I don't want to use my Apple ID with iMessages. I want to continue to use my phone number. If I change to Apple ID people will see my Apple ID when I send a message to them using my phone. And I don't want to share this private information.
So is there some app that will allow me to just copy the whole conversation of my iMessage app to someplace else?