Api development and mobile end development start concurrently

Problem

In our real life software development process.The backend API and mobile development normally developed concurrently.But here is the problem.
In a normal situation the mobile developer will be faster then backend api development.
Then the mobile developer need to wait.

Solution methodology:

Common solution
1.Design api first.
2.Implement a mock server(server that response the data but don’t have the program logic).

Solution for today apiary:
Apiary-Collaborative design, instant API mock, generated documentation, integrated code.

Solution analysis:

Adv:
1.No need to create api mock server.
2.Syntax api look good.
3.Free for open project.

Disadv:
1.Need to learn API Blueprint Syntax Tutorial
2.Because this is mock server,stateful operation can’t be tested properly.(pretty painfull for TDD development)