Do a Google search for "iPhone and Gear S." There's a long thread on another forum that talks about making the two work together. What you can do with the two is very limited.
Many of the apps for the Gear need to be installed via a Samsung phone that has Gear Manager running on it. Once installed some are independent and don't require a phone (EG: calculator, compass). Others only work when connected to a Samsung phone via BT or remotely.
People using non-Samsung Android phones pretty much get notifications and some of those allow responses. Other apps (EG: e-mail, scheduling) don't work at all unless you use the corresponding Samsung app on a connected Samsung phone running Gear Manager. The short of it: to get full functionality from the Gear you need a Samsung phone and ideally use Samsung's apps on it. The further away from that you get the less functionality you'll have on your Gear. Someone said it above, you're an iPhone user so should get an iWatch. People using non-Samsung Android phones or that are all-in with Google's app eco-system should get a Android Wear device. Kind of like why you don't use a screw driver to drive a nail.