require 'storekit'

data = "<Base64-Encoded Receipt Data>"

# This client tries to validate against the production endpoint first. If it
# fails because of error 21007, it automatically validates against the sandbox
# endpoint.
client = StoreKit::FallbackClient.new
client.shared_secret = "really secret string"

begin
  receipt = client.verify! data

  # The raw data
  p receipt.receipt_data

  # Just the IAP receipts
  p receipt.iap_receipts

  # Hash, mapping from original TX IDs to array of transactions sorted in
  # ascending order by purchase date.
  p receipt.receipt_chains

  # Do whatever you need to do to store the purchase state...
rescue StoreKit::ValidationError => e
  # ¯\_(ツ)_/¯
  raise 'no soup for you!'
end