Answer by Dave Hughe:
I use Meta Trader 4 on my Mac and on my iPhone. There is a MT4 app for the iPhone, which works great. As for the Mac, you need a software that allows running windows programs on Mac. Personally, I use CrossOver (Run Windows on Mac, easily and affordably) but there are more good programs out there including free ones such as Wine Skins and Wine Bottler (Run Windows-based Programs on a Mac)