Get the end of a string in a uitextview

I want to create a message box just like Telegram and others chats, that have a time in the down side of the box.

But if the text ends in the end of the line, the time label should be in the next line, otherwise, should stay in the same line.

So, I want something like this:

How to accomplish this in my xib, or programatically ?

Thanks in regards,