I am a long time Xojo fan but I must admit I have not done much iOS development with Xojo. Today I do mostly Web and some desktop and some console utility apps. My only thought is if Jeremie Leroy can write Packr in Xojo (a trip packing list app that is pretty extensive and highly rated on the App Store) then there must not be many limitations where work arounds don't exist.
At this stage you may have to write some Declares and call the specific iOS functions you need. In the future maybe this won't be as necessary but it does give you a path to a solution.
This is by far the best support community I have participated in over my many decades of programming. I suggest you post something here and have the community assist in doing a few declares.
You should also give Geoff some feedback that may help prioritize future features. It is rare in the world of software development tools (or anything) you get a response from the CEO of the company on the community forum because they saw a user with a need. My guess would be most CEOs don't spend much personal time on their own company community forums.
One of the great things about Xojo, beyond the community support, is the ability to use essentially the same syntax for Desktop, Web, and Console apps across Windows, Mac OSX, Linux, and iOS. Xojo is not perfect but it keeps me from having to be fluent in many languages and development tools. In the long run this makes me more productive.
Learning curves can be frustrating but maybe there is still hope.