Apple have made changes to the way hiding the status bar works in iOS 7. If you want your app to be full screen (i.e. minus the status bar), you’ll need to create a customised .plist file, like I’ve described in this article:
This time, you’ll need to add the following to the customised .plist file:
Notes: You’ll still need to set your forms BorderStyle to bsNone. If you’ve already deployed your app to the device, you may need to “uninstall” it in order for the new .plist file to be deployed. Also, if you want the status bar to show while your app is launching, omit the first key, i.e. UIStatusBarHidden, and its value.