Guidecolor doesn't work as string on iOS

[corymsmith]

You have to use processColor first which doesn't match what the docs say. It looks like a similar fix was added for Android a while back. b84d21c

[billdozr]

This is how to directly use processColor for iOS in the mean time to set guideColor:

import {
  Platform,
  processColor
} from 'react-native'

let conf = {
  guideColor: Platform.OS === 'ios' ? processColor(myColor) : myColor
  ...
}

CardIOModule.scanCard(conf).then(card => { ... })

Tested with react-native v0.53.3 (but should work with other versions).