Gets the latest Google Play version code using Fastlane google_play_track_version_codes

latest_googleplay_version_code.rb

def latest_googleplay_version_code
  productionVersionCodes = google_play_track_version_codes(track: 'production')
  betaVersionCodes = google_play_track_version_codes(track: 'beta')
  alphaVersionCodes = google_play_track_version_codes(track: 'alpha')
  internalVersionCodes = google_play_track_version_codes(track: 'internal')

  # puts version codes from all tracks into the same array
  versionCodes = [
    productionVersionCodes, 
    betaVersionCodes, 
    alphaVersionCodes, 
    internalVersionCodes
  ].reduce([], :concat)

  # returns the highest version code from array
  return versionCodes.max
end

Usage:

version_code = latest_googleplay_version_code