colors.js

import {
  PlatformColor,
  DynamicColorIOS as BaseDynamicColorIOS,
  Platform
} from 'react-native'

// Stops this crashing when called on other platforms
const DynamicColorIOS = Platform.select({
  ios: BaseDynamicColorIOS,
  default: () => null
})

export const backgroundColor = Platform.select({
  ios: DynamicColorIOS({light: 'white', dark: 'black'}),
  android: PlatformColor('@color/background')
})
export const textColor = ...