I'm using Objective-C for developing iPhone applications, but I have no idea that which SDK can provide Twitter's streaming API (like receiving new tweets from timeline, notification that someone favorited my tweet, etc.) and OAuth feature.
Is there any SDK for this?
Are you really looking for a SDK? You want something like Objective-C classes wrapping the data in the Twitter streaming API?
It is a web service and you don't really need a SDK. Read the documentation at https://dev.twitter.com/docs/streaming-apis and send requests accordingly.
Get acquainted with the networking parts of Cocoa, for example check out this tutorial: http://cocoawithlove.com/2008/09/cocoa-application-driven-by-http-data.html
To parse the JSON data you get from Twitter's API you can use a parser like SBJson: http://stig.github.com/json-framework/