实现Square类，让其继承自Rectangle类，并在Square类增添新属性和方法，在2的基础上，在Square类中重写Rectangle类中的初始化和打印方法

实现Square类，让其继承自Rectangle类，并在Square类增添新属性和方法，在2的基础上，在Square类中重写Rectangle类中的初始化和打印方法

#import <Foundation/Foundation.h>

@interface Rectangle : NSObject{
    int width;
    int height;
}
@property int width,height;
-(int) area;
-(int) perimeter;
-(void)setWidth:(int)w andHeight:(int)h;
-(void)print;

@end


#import <Foundation/Foundation.h>

@interface Rectangle : NSObject{
    int width;
    int height;
}
@property int width,height;
-(int) area;
-(int) perimeter;
-(void)setWidth:(int)w andHeight:(int)h;
-(void)print;

@end

#import <Foundation/Foundation.h>
#import "Rectangle.h"
@interface Square : Rectangle

-(void) setSide:(int) s;
-(int)side;
-(int)area;
-(int)perimeter;
-(void)print;

@en

#import "Square.h"

@implementation Square

-(void) setSide:(int) s{
    [self setWidth:s andHeight:s];
}

-(int) side{
    return width;
}

-(int)area{
    return width*width;
}

-(int)perimeter{
    return 2*(width+height);
}

-(void) print{
    NSLog(@"side  %d",width);
}

@end