Changing the user interface in iPhone and Android phone

The project is to write an app for iPhone and Android phone. The app will be controlling a micro-controller through ethernet. Normally there are some buttons on the UI to send the signals to micro controller to do the job. In fact, I have done it by myself successfully. Now what I want is so called "interactive" user interface. In other words, user is able to change the layout of buttons position and quantities of the buttons as and when he wish to change. It must be able to achieve changing the parameter in the JSON file. JSON file shall be able to upload to iPhone through Apple iTune on PC for the iPhone. As for Android, JSON file shall be resided in SD drive. Therefore user are able to change parameter in JSON file and upload the file to the phone. I have this idea from the web site that offer an app which utilize the JSON. I want to have my own app exactly same as that one. Please visit [login to view URL] for the more information/understanding. Do let me know if you require more info about the project. I want both app for iPhone and Android phone.