i am making an application in iphone in which i have 4 tabbars & in one of its tab i have 4 views in 2nd view it needs to hide the tab bar. I am able to hide the tab bar
John Smith is correct. The URL for that sample is: http://developer.apple.com/iphone/library/samplecode/TheElements/index.html
The code that does this is in AtomicElementViewController.m, and the line that achieves this effect is in the init method:
self.hidesBottomBarWhenPushed = YES;