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I'll return and expand on each, first siting the tutorial, then adding any editorial needed for my purposes :) (some of these links though are perfect!)

Handling UITextField and the keyboard
http://www.mobisoftinfotech.com/blog/iphone/iphone-uitextfield-tutorial-handling-keyboard-interactions/

so your keyboard is hiding your uitextfield?

http://cocoawithlove.com/2008/10/sliding-uitextfields-around-to-avoid.html

Need to download that stream down to disk so as to not overconsume all your ram?

http://stackoverflow.com/questions/8218362/asihttprequest-ios-properly-download-stream-data-to-disk

Barcode it right with ZBar (opensource barcoding)

http://zbar.sourceforge.net/iphone/sdkdoc/