Multi-Platform Delivery Scheduling App

I'm seeking a proficient app developer to build a delivery block scheduling app, akin to the functionality of Amazon Flex, for both iOS and Android platforms. This app will include:

- User Authentication: Users should authenticate their access via phone number verification procedure.

- Block Scheduling: This feature should be efficiently incorporated to offer users the ability to schedule delivery times.

Ideal freelancers for this project are required to have substantial experience in mobile app development across both iOS and Android platforms, coupled with solid understanding and skill in implementing user authentication systems. Familiarity with delivery services app development will be a plus.