Integrations of an iOS component in React Native

I am new to the development of React Native, I know iOS. Just want to know about few points:

1. Can we add iOS (swift or objective C) code in a React Native App?
2. Can we add React Native Views into the existing iOS app?

I have googled and got the examples which point to that 2nd one is quite possible and Instagram did it in edit profile screen.

But I cannot find examples where it's a React Native app and we introduces swift or Objective-C code in between.

Please if anyone knows of any links or examples available for Case 1, please do let me know about it.

2nd question:

• When we integrate react native with iOS, it will be through a bridge. Let's say I create an app in Swift, to get react native views in it, we have to go through 2 bridges, one converting Swift to Objective-C and then bridge between Objective-C to React Native. Is that correct? If yes will it be as fast as the native app?