You can access email, instant messaging, Office documents, and other Office 365 services from your iPhone or iPad. Instructions for setting up your device are included here and in the Office 365 portal. Go to Settings > Office 365 settings > Get started > Phone & tablet. Or, you can go to Software > Phone & tablet. Choose iPhone or iPad.
You can get apps for both SharePoint and Lync (Lync: An Office program that provides instant messaging, a contact list, audio and video conversations, online meetings, desktop sharing, and more.) in the Office 365 portal or go to the App Store.
Set up email on Apple iPhone, iPad, and iPod Touch
OWA for iPhone and OWA for iPad
For viewing and on-the-go editing Microsoft Office Mobile Help
For viewing only Use Office Web Apps on your iPhone
Lync for mobile clients
Open a SharePoint Online site on an iPhone or iPad