Is it possible to have an “inline button” on a channel that says “invite a friend” that forwards the private channel URL to friends on the channel. The idea is to make the “invitation process” for users to invite their friends much easier.
Yes . Go to channel and then click on manage channel
then click on channel type
and you will see a pop-up that you can select your channel type as Public Channel
or Private Channel
.
In the below of the form you can see Invite link
. So you can copy it and give it to your friends or have an "Join channel" button with that refer to that link.
Here is a link that you can read more about URL buttons
and here is API link
These screen shots are also useful :