Barcode Scanner Programmer

I want a simple app that can scan a QR or barcode, and when it is scanned it send a request to my server and find out whatever the barcode has been used, like a ticket system. After the scanning, my code will send data back, with information about the ticket is used or not, and make a simple popup on the users phone that indicate the ticket status, and when the user click on the popup it closes and go back to the scanner. The person who is going to use this app, shall use as less clicks as possible and it should take as less time as possible to scan and check the status of the ticket, before a new ticket is ready to be scanned. The web app shall be used as a ticket system for events, and must be possible to use with both Android and IOS. The web app shall be very simple, and i will make the design my self, so you shall just make the functionality. The application is using Rails 3.2.3. It is using the Devise gem for authentication, Rollify for defining roles, Can-Can for defining abilities. If more information is needed, please let me know.