Visio diagrams look great on your iPhone, all along with an intuitive pan and zoom experience optimized for touch. The Microsoft Visio Viewer designed for iPhone.
To create or edit diagrams, you will need Visio Pro for Office 365 subscription, which also gives you access to the full Visio experience on Windows desktop. You can also share the diagrams with anyone who can then view Visio diagrams on their iPhone or in a web browser even they don’t have Visio installed on their Windows desktop. Sign in with your Microsoft Account or open a Visio attachment from email, and enjoy the amazing view of Visio diagrams on any iPhone running iOS 9.0 or later.
You can view and interact with Visio diagrams on iPhone on the go for free. Microsoft Visio Viewer for diagrams and flowcharts