业务练习（矩形）

Sian

需求分析：
写一个Rectangle类，具备以下属性：位置（origin）、长（width）、宽（height）
要求提供：初始化方法、工厂方法、业务方法（移动位置、求周长、求面积）
程序实现：说明：我们程序实现中写两个类SAPoint与SARectangle，SAPoint专为矩形提供位置服务（矩形的一个属性）
SAPoint.h

1. //
2. //  SAPoint.h
3. //  Rectangle
4. //
5. //  Created by yusian on 14-1-18.
6. //  Copyright (c) 2014年 yusian. All rights reserved.
7. //
9. #import <Foundation/Foundation.h>
11. @interface SAPoint : NSObject
12. @property int x;
13. @property int y;
14. - (id) init;
15. - (id) initWithX:(int)x andY:(int)y;
16. + (id) pointWithX:(int)x andY:(int)y;
17. - (void) show;
18. @end

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SAPoint.m

1. //
2. //  SAPoint.m
3. //  Rectangle
4. //
5. //  Created by yusian on 14-1-18.
6. //  Copyright (c) 2014年 yusian. All rights reserved.
7. //
9. #import "SAPoint.h"
11. @implementation SAPoint
13. - (id) init
14. {
15.     if (self = [super init]) {
16.         _x = 1;
17.         _y = 1;
18.     }
19.     return self;
20. }
22. - (id) initWithX:(int)x andY:(int)y
23. {
24.     if (self = [super init]) {
25.         self.x = x;
26.         self.y = y;
27.     }
28.     return self;
29. }
31. + (id) pointWithX:(int)x andY:(int)y
32. {
33.     return [[SAPoint alloc] initWithX:(int)x andY:(int)y];
34. }
36. - (void) show{
37.     NSLog(@"The position is (%d,%d)",_x,_y);
38. }
40. - (void) dealloc
41. {
42.     NSLog(@"SAPoinr is dealloc");
43.     [super dealloc];
44. }
46. @end

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SARectangle.h

1. //
2. //  SARectangle.h
3. //  Rectangle
4. //
5. //  Created by yusian on 14-1-18.
6. //  Copyright (c) 2014年 yusian. All rights reserved.
7. //
9. #import <Foundation/Foundation.h>
10. #import "SAPoint.h"
12. @interface SARectangle : NSObject
14. @property int width;
15. @property int height;
16. @property (assign) SAPoint *origin;
18. - (id) initWithPoint:(SAPoint *)origin andWidth:(int)width andHeight:(int)height;
19. + (id) rectangleWithPoint:(SAPoint *)origin andWith:(int)width andHeight:(int)height;
20. - (void) show;
21. - (void) moveToX:(int)x andY:(int)y;
22. - (int) perimeter;
23. - (void) perimeterPrint;
24. - (int) area;
25. - (void) areaPrint;
26. @end

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SARectangle.m

1. //
2. //  SARectangle.m
3. //  Rectangle
4. //
5. //  Created by yusian on 14-1-18.
6. //  Copyright (c) 2014年 yusian. All rights reserved.
7. //
9. #import "SARectangle.h"
11. @implementation SARectangle
13. - (id) initWithPoint:(SAPoint *)point andWidth:(int)width andHeight:(int)height
14. {
15.     self = [super init];
16.     if (self) {
17.         self.origin = point;
18.         self.width = width;
19.         self.height = height;
20.     }
21.     return self;
22. }
23. + (id) rectangleWithPoint:(SAPoint *)point andWith:(int)width andHeight:(int)height
24. {
25.     return [[SARectangle alloc] initWithPoint:(SAPoint *)point andWidth:(int)width andHeight:(int)height];
26. }
28. - (void) moveToX:(int)x andY:(int)y
29. {
30.     _origin.x = x;
31.     _origin.y = y;
32.     NSLog(@"The new position is (%d,%d)",_origin.x,_origin.y);
33. }
34. - (int) perimeter
35. {
36.     return (self.width+self.height)*2;
37. }
39. - (void) perimeterPrint
40. {
41.     NSLog(@"The Perimeter is %d",self.perimeter);
42. }
44. - (int) area
45. {
46.     return self.width*self.height;
47. }
49. - (void) areaPrint
50. {
51.     NSLog(@"The area is %d",self.area);
52. }
54. - (void) show
55. {
56.     NSLog(@"The rectangle position is (%d,%d) , Width is %d , Height is %d",_origin.x,_origin.y,self.width,self.height);
57. }
58. - (void) dealloc
59. {
60.     NSLog(@"SARectangle is dealloc");
61.     [_origin release];
62.     [super dealloc];
63. }
65. @end

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main.m

1. //
2. //  main.m
3. //  Rectangle
4. //
5. //  Created by yusian on 14-1-18.
6. //  Copyright (c) 2014年 yusian. All rights reserved.
7. //
9. #import <Foundation/Foundation.h>
10. #import "SAPoint.h"
11. #import "SARectangle.h"
13. int main(int argc, const char * argv[])
14. {
15.    
16.     @autoreleasepool {
17.         
18.         SAPoint * point = [SAPoint pointWithX:2 andY:4];//工厂方法
19.         [point show];
20.         
21.         SARectangle * rectangle = [SARectangle rectangleWithPoint:point andWith:10 andHeight:20];
22.         
23.         [rectangle show];
24.         [rectangle perimeterPrint];
25.         [rectangle areaPrint];
26.         [rectangle moveToX:3 andY:5];
27.         [rectangle release];
28.         
29.     }
30.     return 0;
31. }

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输出结果：

1. 2014-01-18 18:25:40.178 Rectangle[6671:303] The position is (2,4)
2. 2014-01-18 18:25:40.179 Rectangle[6671:303] The rectangle position is (2,4) , Width is 10 , Height is 20
3. 2014-01-18 18:25:40.180 Rectangle[6671:303] The Perimeter is 60
4. 2014-01-18 18:25:40.180 Rectangle[6671:303] The area is 200
5. 2014-01-18 18:25:40.180 Rectangle[6671:303] The new position is (3,5)
6. 2014-01-18 18:25:40.181 Rectangle[6671:303] SARectangle is dealloc
7. 2014-01-18 18:25:40.181 Rectangle[6671:303] SAPoinr is dealloc
8. Program ended with exit code: 0

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Sian

该程序还存在内存管理问题：
在声明SAPoint对象时，没有将SAPoint进行内存管理
因此，在@property (assign) SAPoint * origin 时需要优化，最简单的方法在声明时使用retain属性
修改成：@property (retain)SAPoint * origin;
main.m中创建point后，将point被调用后，负责创建point的指针有责任将point释放，因此需要在
ARectangle * rectangle = [SARectangle rectangleWithPoint:point andWith:10 andHeight:20];后加上[point release];