I see that there is an Android project in phabricator.com but there is no iOS or Windows project.
Will there be any mobile clients for Phabricator?

It will be helpful if one can comment existing tasks and mocks on his/her phone. It is extremely helpful that one can receive notifications via phone that someone replies or comments on his/her tasks/diff/commit.

Although Phabricator is optimized for mobile Web and I can add the link to home screen, it is still not as convenient as an app.

For example, there is only one instance of Safari running and if I need to browse other websites, I have to navigate away from Phabricator and next time I browse Phabricator, the whole page will load again. If I am using the Phabricator iOS app, the app will restore its state immediately and I can quickly switch between Phabricator app and my Safari webpage.