I did not try iOS on Xojo more than easy tries ... but I'm pretty sure you can do a lot of things with declares.
problem: you need to know how to write the declares, and for that you need to know objective C and XCode and its framework.
so the idea would be to do it in XCode, then immediately convert it to xojo declares, and then use it with Xojo.
but that is what ioskit (should) contain ?
there must some things you cannot do with declares, these things should be known and isolated and listed somewhere.