Asking Questions About Classes

refer to Addison Wesley - Programming.in.ObjectiveC.2.0.2nd (2009)
詢問確認 class的資訊

#import “ Square.h ”
int main (int argc, char *argv[])
{
NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
Square *mySquare = [[Square alloc] init];
// isMemberOf:
if ( [mySquare isMemberOfClass: [Square class]] == YES )
NSLog (@ ” mySquare is a member of Square class ” );
if ( [mySquare isMemberOfClass: [Rectangle class]] == YES )
NSLog (@ ” mySquare is a member of Rectangle class ” );
if ( [mySquare isMemberOfClass: [NSObject class]] == YES )
NSLog (@ ” mySquare is a member of NSObject class ” );
// isKindOf:
if ( [mySquare isKindOfClass: [Square class]] == YES )
NSLog (@ ” mySquare is a kind of Square ” );
if ( [mySquare isKindOfClass: [Rectangle class]] == YES )
NSLog (@ ” mySquare is a kind of Rectangle ” );
if ( [mySquare isKindOfClass: [NSObject class]] == YES )
NSLog (@ ” mySquare is a kind of NSObject ” );
// respondsTo:
if ( [mySquare respondsToSelector: @selector (setSide:)] == YES )  // 注意 :
NSLog (@ ” mySquare responds to setSide: method ” );
if ( [mySquare respondsToSelector: @selector (setWidth:andHeight:)] == YES )
NSLog (@ ” mySquare responds to setWidth:andHeight: method ” );
if ( [Square respondsToSelector: @selector (alloc)] == YES )
NSLog (@ ” Square class responds to alloc method ” );
// instancesRespondTo:
if ([Rectangle instancesRespondToSelector: @selector (setSide:)] == YES)
NSLog (@ ” Instances of Rectangle respond to setSide: method ” );
if ([Square instancesRespondToSelector: @selector (setSide:)] == YES)
NSLog (@ ” Instances of Square respond to setSide: method ” );
if ([Square isSubclassOfClass: [Rectangle class]] == YES)
NSLog (@ ” Square is a subclass of a rectangle ” );
[mySquare release];
[pool drain];
return 0;
}

mySquare is a member of Square class
mySquare is a kind of Square
mySquare is a kind of Rectangle
mySquare is a kind of NSObject
mySquare responds to setSide: method
mySquare responds to setWidth:andHeight: method
Square class responds to alloc method
Instances of Square respond to setSide: method
Square is a subclass of a rectangle