This project takes a lot from this and makes changes for the new API (you must register your SharePoint application with Azure AD). This document sets up Azure AD for Sharepoint Online.
When using the ADAL package on the Xamarin iPhone emulator, it requires quite a process to get up and running. Installing ADAL requires the NuGet Package “Microsoft.IdentityModel.Clients.ActiveDirectory”. Once that’s installed, you must create an authenticator service to assist with authenticating.