How it works
Step 1: Click on the app which you want to hide. The data of this app wouldn't be deleted in this process.
Step 2: An alert will be shown. Click on the "Install"-button.
Step 3: The device couldn't install the app. But this isn't a problem. In the next alert, you must click on "Done".
Step 4: The downloaded app has overwritten the preinstalled app. So you must only delete the downloaded app and you're done. To reactivate the preinstalled app, you must only reboot your iOS device.
iAd works exactly the same.
Step 2: An alert will be shown. Click on the "Install"-button.
Step 3: The device couldn't install the app. But this isn't a problem. In the next alert, you must click on "Done".
Step 4: The downloaded app has overwritten the preinstalled app. So you must only delete the downloaded app and you're done. To reactivate the preinstalled app, you must only reboot your iOS device.
iAd works exactly the same.