The best way to control the Q5 (or Q10, M3 or any Android box) is a wireless mouse or other pointing device. Unless you plan on doing a lot of typing a mouse works great. Most mice are compatible and we sell a few airmice/trackpads. The Rii Mini i8+ is a great product. http://www.futeko.com/browse.php?cat=rem
There is no iPhone app for the Q5. If you had an Android device then the HiControl app (http://www.futeko.com/newforum/index.php?topic=56.msg104#msg104) does exactly what you require, but HiMedia have no plans for an iOS version.
There are various Kodi remotes available for iOS which will work with Kodi on the Q5. e.g. this official one: http://kodi.wiki/view/Official_Kodi_Remote/iOS