getters and setters

- (id)foo {

　　return foo;

}

 

- (void)setFoo:(id)aFoo {

　　if(aFoo != foo) {

　　　　[aFoo retain];

　　　　[foo release];

　　　　foo = aFoo;

　　}

}

@property

@synthesize    in the implementation file

Button_FunViewController.m

we will tell the compiler to create the getter and setter methods at compile time.