关于对象动态类型的一些问题 Object-C 2.0
关于对象动态类型的一些问题 Object-C 2.0
To get a class object from a class named Square , you write the following:
[Square class]
If mySquare is an instance of Square object, you get its class by writing this:
[mySquare class]
如果想从Square类得到一个类的对象（实例）可以用[Square class];
如果mySquare是Square类的一个实例，那么如果想得到它对应的class 可以[mySquare class]
下面是一些示例代码：
#import "Square.h"int main(int argc, char *argv[]){NSAutoleasePool *pool = [[NSAutoleasePool alloc] init];Square *mySquare = [[Square alloc] init];// isMemberOfif([mySquare is MemberOfClass: [Square class]] == YES){NSLog(@"mySquare is a memeber 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");}// isKindOfif([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){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");}// instancesRespondToif([Rectangle instancesRespondToSelector: @selecotr(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;}输出：
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