iOS tutorial
http://developer.apple.com/library/ios/#referencelibrary/GettingStarted/GS_iPhoneGeneral/_index.html#//apple_ref/doc/uid/TP40007853
cocoa foundation:incl basic of obj c
http://developer.apple.com/library/ios/#documentation/Cocoa/Conceptual/CocoaFundamentals/Introduction/Introduction.html#//apple_ref/doc/uid/TP40002974
Todo:
make memo of Inakage Seminar memo finished.