App developer experts in both android and IOS

We are launching an app (on IOS and Android) and looking for a developer to work with us during the soft opening just in case something pops up or when updates are needed.
Nature of issues are not clear yet.

Applicants should be;

Responsive
Expert in IOS and Android
Shows excitements to coop with a start up project. This may result in a renewed coop.
Strictly and obliged by law to keep the source code secure and safe.

Thanks