I'm using User Stream and Instead of pull-to-refresh to check for new tweets or waiting for the 5 minute auto-refresh to take place, I want tweets appear instantly in timeline as they are published.
I'm using TweetSharp with Xamarin.IOS
Any Code Sample will help a lot even if with other Programing Lang
I can't really help you with the Xamarin part of it, since I haven't used any of the Xamarin tools, but you want to use the Streaming part of TweetSharp to handle this. See this section for the classes you'll probably want to use:
https://github.com/danielcrenna/tweetsharp/blob/master/src/TweetSharp/TwitterService.Streaming.cs
Here is a code sample of using streaming in TweetSharp: https://gist.github.com/kensykora/8005935
See the official twitter docs on their streaming here: https://dev.twitter.com/docs/streaming-apis