Vitruvius does not have a native iOS application and has no plans of developing one. This is due to consistent surveying of our user base reporting 95% or higher use of Microsoft products.
There are many users successfully using Vitruvius applications on iOS by using Parallels. See this article from Apple.
Vitruvius is actively developing web applications as the future of its platform, however, there is no date when these may start to become available.
The Vitruvius Team