interface builder and nib

the application's GUI is designed by interface builder

GUI is defined in the nib file.  

Use interface builder to open nib file & design gui

define class used in the nib

IBOutlet

instance variable points to other object is called outlet

ex:

IBOutlet  NSTextField *testField;

IBAction

the method is called by user interface objects

ex:

-(IBAction)seed:(id)sender;

create an object instance:

1. drag object from Library window to doc window

2. set its class to object's class name in the Identity Inspector

make connection:

connect two objects

ex:

a object has outlet textFiled of type TextField , then connect textFiled to  TextFiled GUI

ex:

when button b is pressed, it calls the method test in object c. Then connect b to object c's methods test

awakeFromNib:

all objects are sent the message awakeFromNib after the objects in nib file are brought to life

Hence, we can do something in awakeFromNib to init GUI