Useful or not, from you.
react-native-slider Native Component for "RNCSlider" does not exist.

I already installed it and import it but this error shows "Native Component for "RNCSlider" does not exist."

That's a useful answer
Without any help

I had the same issue and for me this was due to the fact that I had overridden the ReactPackages in MainApplication.getPackages(). I had to add new ReactSliderPackage(); (imported from com.reactnativecommunity.slider.ReactSliderPackage;) to the returned list to fix this.

I don't know the iOS variant for this but the idea is that you have to ensure your native code advertises all the native packages you need, including your dependencies. react-native link doesn't do that (and should probably warn about ?).