I built a custom sharer module on iOS Safari. Without using iOS8 latest Action module, I used bookmark to emulate this function.
I had already sharer module in my Apps, that shows a window, enter text, embed link, and share to many social sites, such as Facebook and Twitter. I had another module so called GooGLShortenURL that can request shorten URL from goo.gl, embed in my text, share to Twitter which had character limit (140 characters).
I then have my code to handle incoming URL scheme request.
In my handler, interpret the incoming URL scheme request, based on parameters, fire up Sharer module, then start sharing. I can share to many social sites just in one click.