Your question is a bit vague, however I will try to answer anyway. At the moment, only the API that I know that provides access to Windows Live services using Objective-C applies to the Live SDK for iOS
The iOS’s Live SDK is designed to help developers easily integrate SkyDrive and Hotmail contacts and calendars into their iOS apps.
The repository includes:
Live SDK Library Source (src / LiveSDK / Library) Live SDK Frame (bin / LiveSDK.framework.zip) Samples (src / samples)
You can purchase documentation and additional assistance from the Live Connect Development Center .