In my application I need to use the Windows Azure services to store the data for that I am using this:http://www.windowsazure.com/en-us/develop/mobile/tutorials/get-started-
REST API maybe better for iOS devices. Azure SDK does not have object-c support as good as C# I am afraid.
http://msdn.microsoft.com/en-us/library/windowsazure/dd135733.aspx