Uhhmm. Construct 2 is currently only usable in WIndows OS. Ashley (Co-Founder of C2) promised that he will include support for Apple OS & Linux on C3 (which will be released someday).
I don't own a MAC so I don't know what extensions you use, but I believe it won't come out as an app, it will only come out as an installer file.
And I believe you can't use an IPAD to make games, practically. It's not designed to do that.