I would like first to express the gratitude to this great community for the feedback that it has provided in my initial post (https://www.applevis.com/forum/ios-ios-app-discussion/introducing-speech...) regarding my app Speech Central, which is available at the App Store: https://itunes.apple.com/us/app/speech-central-web-text-to/id1127349155?... .
Thanks to that feedback there have been many improvements in the accessibility of the app like support for DAISY format, new navigation functions that can be assigned to audio control buttons, audio messages for some changes in the interface, labels for some tables etc. But one really notable feature that is worth to be announced separately is the integration with the Bookshare service that also came as the result of the user request. The app now allows the user to log in to the Bookshare service, search books and import them to the app.
The app has a free tier and you can access Bookshare books with it with limitation that only one book can be imported at a time (to import new one you need to delete the last one) and that you can't add more than two books in one day.
Customizable audio button shortcuts should make the imported book quite accessible, you can use them with stock iPhone headphones for moving to the next/previous sentence, paragraph, 30 seconds period, title, bookmark, chapter or book.
I am looking forward for further suggestions and hope to add more useful features like this one in the future.