App development - iOS and Android

Require a programmer/app developer who knows how to make a smartphone app that works seamlessly on both iOS and Android, [also Windows Phone, if possible]) Project: Build a Messaging App using Telegram APIs already provided. API key will be provided. App icon will be provided. Will tell you what features to include and not include, and what the User Interface should look like. Duration: Should take you around 3-4 hours. This app is for corporate use and therefore requires you to sign a non-disclosure agreement.