用继承实现XYPoint和Circle两个类
1 #import <Foundation/Foundation.h> 2 @protocol show 3 @required 4 -(void)printOn; 5 @end 6 7 @interface XYPoint : NSObject<show>{ 8 int x; 9 int y; 10 } 11 @property (nonatomic,assign)int x,y; 12 -(id)setX:(int)_x andY:(int)_y; 13 14 @end 15 16 #import "XYPoint.h" 17 18 @implementation XYPoint 19 @synthesize x,y; 20 21 -(id)setX:(int)_x andY:(int)_y{ 22 self.x=_x; 23 self.y=_y; 24 return self; 25 } 26 -(void)printOn{ 27 NSLog(@"x = %d ,y = %d",x,y); 28 } 29 @end 30 31 #import <Foundation/Foundation.h>
32 #import "XYPoint.h" 33 @interface Circle : XYPoint<show>{ 34 int radius; 35 } 36 @property (nonatomic,assign)int radius; 37 -(id)initWithX:(int)_x andY:(int)_y andRadius:(int)_r; 38 -(double)area; 39 -(double)perimeter; 40 @end 41 42 #import "Circle.h" 43 44 @implementation Circle 45 @synthesize radius; 46 -(id)initWithX:(int)_x andY:(int)_y andRadius:(int)_r; 47 { 48 self.x=_x; 49 self.y=_y; 50 self.radius=_r; 51 return self; 52 } 53 54 -(double)area{ 55 return 3.14*radius*radius; 56 } 57 58 -(double)perimeter{ 59 return 2*3,14*radius; 60 } 61 62 -(void)printOn{ 63 NSLog(@"x = %d, y = %d ,radius = %d",x,y,radius); 64 65 } 66 @end