Here's a quote from a Computer World article posted January 10, 2014 by Fred O'Connor:
In the mobile space, experience with developing for Apple's iOS leads the way
in desired backgrounds, said John Reed, senior executive director at
staffing firm Robert Half Technology.
There's also some demand for other platforms like Microsoft's Windows
Phone, he said.
Understanding how to create a site that can be easily viewed and navigated
from a handheld device is just as important to employers as knowing how to
develop a mobile application, he added.
Developers with Google Android experience are also sought after, said Schade.