I just found a great app that can let you control to display the apps on your child's iPhone/iPad. The name of the app is 'ParentKit'. I have understood what the app is doing but don't know how it is doing.
It is basically accessing the 'Restrictions' Settings in the ios default settings Menu by installing a Provisioning Profile on your child's iPhone with the help of web browser? Could someone explain how to do this in your own app?