Apple - Objective-C primer:
http://developer.apple.com/library/ios/#referencelibrary/GettingStarted/Learning_Objective-C_A_Primer/_index.html
Apple Objective-C Programming language:
http://developer.apple.com/library/ios/#documentation/Cocoa/Conceptual/ObjectiveC/Introduction/introObjectiveC.html
Apple OO with Objective-C:
http://developer.apple.com/library/ios/#documentation/Cocoa/Conceptual/OOP_ObjC/Introduction/Introduction.html
Cocos 2d official documentation (includes lots of tutorials, best practices etc):
http://www.cocos2d-iphone.org/wiki/doku.php/
Ray Wenderlich's great site:
http://www.raywenderlich.com/tutorials
In particular:
http://www.raywenderlich.com/352/how-to-make-a-simple-iphone-game-with-cocos2d-tutorial
http://www.raywenderlich.com/692/rotating-turrets
http://www.raywenderlich.com/782/harder-monsters-and-more-levels
http://www.raywenderlich.com/1163/how-to-make-a-tile-based-game-with-cocos2d
http://www.raywenderlich.com/1271/how-to-use-animations-and-sprite-sheets-in-cocos2d
http://www.raywenderlich.com/3611/how-to-make-a-space-shooter-iphone-game
Physics - Box 2d
http://www.raywenderlich.com/457/intro-to-box2d-with-cocos2d-tutorial-bouncing-balls
http://www.raywenderlich.com/606/how-to-use-box2d-for-just-collision-detection-with-cocos2d-iphone
Apple XCode User guide:
http://developer.apple.com/library/ios/#documentation/ToolsLanguages/Conceptual/Xcode4UserGuide/Introduction/Introduction.html
http://www.lostgarden.com/search/label/free%20game%20graphics
http://www.widgetworx.com/widgetworx/portfolio/spritelib.html
http://www.reinerstilesets.de/
http://www.vickiwenderlich.com/category/free-art/
http://www.gamedev.net/topic/272386-sprites-sprites-and-more-sprites/
http://www.mapeditor.org/index.html
http://gamesfromwithin.com/prototyping-youre-probably-doing-it-wrong
http://www.gamasutra.com/view/feature/2438/how_to_prototype_a_game_in_under_7_.php
http://www.youtube.com/watch?v=aW6vgW8wc6c
(skip the boring stuff, start at 1:37 in)
http://chrishecker.com/Advanced_Prototyping
http://gamedesignconcepts.wordpress.com/
http://bbrathwaite.wordpress.com/
The Art of Game Design: a book of Lenses (in Lab B at the front)