Due to limitations in IOS itself, normal screen sharing is not allowed in the same way that can be done in Android and on the web. There are some workarounds as follows:
One workaround is to quickly capture a series of still images of the screen and send those images across continuously. To do this for the whole session is quite bandwidth and CPU intensive. Its also not as smooth as normal screen sharing. So you have to weigh the benefits of screen sharing vs the quality of the user experience.
A second workaround is to do the same to capture key moments, rather than the whole session. For example, to capture someone signing a document, or acknowledging the terms of a form and clicking the submit button. This allows you to share and record key moments while also retaining a good user experience.