how to save .zip file in iphone app

in my app when user press Download button, then .zip file will be downloaded and should be save on device.

1. how to store streaming data into .zip file? and
2. where to store this .zip file so user can unzip file and see the data of file?

I am using NSURLConncetion to download .开发者_如何转开发zip file

thank you in advance

to save and unzip file on iphone read this - http://www.touch-code-magazine.com/update-dynamically-your-iphone-app-with-new-content/