I believe that the answser is simple, but I can't find any useful updated answer.
With Facebook you can easily share a link using this url:
https://www.facebook.com/sharer/sharer.php?u=http://stackoverflow.com
And with Twitter, you can easily share a tweet using this other format:
https://twitter.com/intent/tweet?text=hello%20this%20is%20a%20tweet
(You can click on the links to see the result)
The thing is, in twitter you can see that I can specify the text of the post directly in the url. But I don't know how to do this on Facebook.
There's a way to do this, with Facebook? I don't want that the user share any URL, but a post with a default text.
Thanks in advance!