There is a current iOS app which works for iPad to display the limited features of a Web one version of one application (already in place and no changes needed here). However this iPad version support only streaming from Hikevision cameras for which sdks are in place.
What is needed is to make the same app port to iOS 11 which should also work with NVRs with video cards manufactured by Chance-I (later known as DiViS). Unfortunately we do not have any sdks for iOS version of this and have to see what can be done to make it work. Besides this new app should work on latest iOS on iPhone.