Ozi is not yet available for any Apple product. Closest you will get is the HEMA, Memory Maps or BitMap if you are looking for something like Ozi.
As NissanGQ posted, if you get the MUDMaps HD app for the Ipad, you can load it on the Iphone as well but if you get the standard version of MUDMaps for the Iphone, the screen resolution is out of whack on the Ipad. Benefit of the HD version is there are are no subscription fees unlike the standard version and all the maps are included and additional ones are available to purchase.
MUDMaps are currently trialling an updated UI and small changes to the app itself which will make the app a lot better to use and streamline some of the processes, I am currently trialling the BETA version at the moment to find any bugs before it goes to the public release