The IOS Skype for Business App has been updated to version 6.7. The update brings Video-based Screen Sharing (VbSS) to mobile devices.
The description released with the update is below
"With this update, we are bringing Video-based Screen Sharing (VbSS) to your mobile devices. A faster and more reliable way of viewing content in a meeting, Vbss is a great improvement over the traditional approach of content sharing. In addition, we also have some design and performance improvements"
If you have enabled the relevant option the app update should be installed automatically if not then you will need to select the update from the Updates menu in the Apps Store.