[iPhone] Interface Builder

1. Tutorial:
   
   • Interface Builder User Guide
     http://developer.apple.com/iphone/library/documentation/DeveloperTools/Conceptual/IB_UserGuide/Introduction/Introduction.html
   • xxx
     
2. Introduce
   Interface Builder(IB) is a visual tool to help design your UI.
   
3. Launch Interface Builder
   On Xcode, double click the file end with extension .xib
   
4. What's In Nib
   
   • File's Owner
     It represents the object that loads the Nib file from disk. In other word, File's Owner is the object that owns this copy of Nib file.
     
   • First Responder
     A responder object is an object that can respond to events and handle them. UIResponder is the base class for all responder objects, also known as, simply, responders.
     
     The First Responder represents the object with which the user is currently interacting. In other word, it is the current focused control. ie., the user is currently enterring data into a text field, that field is current First Responder.
     
     The First Responder changes as the user interacts with the interface, and First Responder gives your convenient way to communicate with whatever control or view  is the current first responder without having to write code to determine which control or view that might be.
   • Other icon
     Other icon in this widow represents an object instance that will be created when the nib file loads.
     
5. The Window Interface Builder
   
   • Library
     You can press menu Tools > Library to open library window. This is you will find all the stock Cocoa Touch objects that Interfacce Builder supports.
     
   • Inspector
     You can pressmenu Tools > Inspector to open inspector window. On inspector, you can set the attributes of the currently selected item.
     
   • ...
     
6. Defien outlets in .h file
   IBOutlet UIButton *myButton;
   
   The IBOutlet keyword is defined like this:
   #ifndef IBOutlet
   #define IBOutlet
   #endif
   IBOutlet doesn absolutely nothins, it sole purpose is to act as a hint to tell Interface Builder that this is an interface variable that we are connect to an object in a nib file must be proceded by the IBOutlet keyword.
   
7. Define action method
   - (IBAction) doSomethins:(id)sender;
   or
   - (IBAction) doSomethins;
8. ...