One clarification here. Drifty/Ionic is not native...it's "hybrid", which means it simply wrapping AngularJS into a native container.
React Native actually compiles Obj-C (much like Xamarin) which is what makes it fairly revolutionary. In other words, it would be very difficult to tell the difference between someone writing native Obj-C with someone compiling it from React Native. Drifty/Ionic is simply doing transitions, taps, using the JS engine of the phone.