Hello,
First of all please BEWARE and alerted about most of the users who just spam their bids on projects without reading or discussing it with the employers usually.
Secondly, what you asked is not possible normally in iOS programming as Apple doesnt allow it. Donot believe any freelancer saying he can program such a app for you, it is simple not possible in iOS due to Apple guidelines and limitations.
Thirdly, only way to do this would be on Jailbroken iphones. If you use a Jailbroken device (80% users JB their device eitherway) then it is possible.
This app cannot be submitted or accepted on Apple App Store as well as I mentioned above.
So as long as the app is for private use or for friends who can directly install the file or use jailbroken devices, this can be done.
I would be glad to work with you on this project if you would like to and would be happy to explain more on the points I mentioned above if you would like to know.
Though it will be better if you can provide me a bit more details on app usage and the things I mentioned above.
Regards