iOS Real-Time Concert Seat App

I’m staging a small concert and need a lightweight iOS app that lets attendees choose their seats—nothing more. There is no cart, checkout, or payment flow; the sole purpose is to display a seating chart, let a guest tap a seat, and lock that seat the instant it’s chosen so nobody else can grab it... (Budget: €30 - €250 EUR, Jobs: App Design, Backend Development, iOS Development, iPhone, JavaScript, Mobile App Development, Objective C, Swift)