Objective-C复合
正所谓复合，便是定义的这个类中的成员是另外类的实例方法。
也就是把其他对象作为自身的题部分，以提升自身的功能，
就相当于C语言中的函数嵌套。下面是一段代码(多个文件放在一块了):
1 /***Computer类的声明***Computer类的声明***Computer类的声明***/
2 #import <Foundation/Foundation.h>
3
4 @interface Computer : NSObject
5
6 @property (nonatomic, strong) NSString *brand;//声明一个字符串对象属性brand
7
8 @end
9
10 /***Computer类的实现***Computer类的实现***Computer类的实现***/
11 #import "Computer.h"
12
13 @implementation Computer
14
15 @end
16
17 /***Desk类的声明***Desk类的声明***Desk类的声明***/
18
19 #import <Foundation/Foundation.h>
20
21 @interface Desk : NSObject
22
23 @property (nonatomic, strong) NSString *color;//声明一个字符串对象属性color
24
25 @end
26
27 /***Desk类的实现***Desk类的实现***Desk类的实现***/
28
29 #import "Desk.h"
30
31 @implementation Desk
32
33 @end
34
35 /***ClassRoom类的声明***ClassRoom类的声明***ClassRoom类的声明***/
36
37 #import <Foundation/Foundation.h>
38 #import "Desk.h"
39 #import "Computer.h"
40
41 @interface ClassRoom : NSObject
42 @property (nonatomic, strong) Desk *desk;//声明一个Desk的对象desk的属性 这里用的就是复合
43 @property (nonatomic, strong) Computer *computer;////声明一个Computer的对象computer的属性这里用的也是复合
44 @end
45
46 /***ClassRoom类的实现***ClassRoom类的实现***ClassRoom类的实现***/
47
48 #import "ClassRoom.h"
49 @implementation ClassRoom
50 -(NSString *)description{ //库方法，方法的重写
51 NSString *str = [NSString stringWithFormat/*方法*/:@"我们的教室有%@的桌子，%@电脑",self/*当前方法的调用者-ClassRoom*/.desk.color,self.computer.brand];
52 return str;
53 }
54 @end
55
56 /***主函数***主函数***主函数***主函数***主函数***主函数***主函数*/
57
58 #import <Foundation/Foundation.h>
59 #import "ClassRoom.h"
60
61 int main(int argc, const char * argv[]) {
62 @autoreleasepool {
63
64 ClassRoom *classRoom = [[ClassRoom alloc] init];
65 Desk *de= [[Desk alloc] init];
66 classRoom.desk = de;//给对象的属性（类的对象）赋值，先初始化该属性
67 classRoom.desk.color = @"褐色";//给属性的属性赋值
68
69 Computer *com = [[Computer alloc] init];
70 com.brand = @"黑苹果";//对象完全初始化之后，再给其所属的对象赋值
71 classRoom.computer = com;
72
73 NSLog(@"%@",classRoom);
74 }
75 return 0;
76 }
另一个例子:
1 #import <Foundation/Foundation.h>
2 //门类
3 @interface Door:NSObject
4 -(void)open;
5 -(void)close;
6 @property(nonatomic,strong)NSString *replace; //实现更换门
7 @end
8 @implementation Door
9 -(void)open
10 {
11 NSLog(@"开门");
12 }
13 -(void)close
14 {
15 NSLog(@"关门");
16 }
17 -(void)color
18 {
19 NSLog(@"门得颜色%@",self.replace);
20 }
21 @end
22
23 //窗户类
24 @interface Window:Door
25 @end
26 @implementation Window
27 -(void)open
28 {
29 NSLog(@"开窗");
30 }
31 -(void)close
32 {
33 NSLog(@"关窗");
34 }
35 @end
36 //房屋类
37 @interface Housing:NSObject
38 //{
39 // Door *door;//门
40 // Window *window;//窗户
41 //}
42 @property(nonatomic)Door *door;//门
43 @property(nonatomic)Window *window;//窗户
44 -(void)InAndOut;//进出方法
45 -(void)takeAbreath;//换气方法
46 @end
47 @implementation Housing
48 -(void)InAndOut
49 {
50 // door = [[Door alloc] init];
51 NSLog(@"进屋");
52 [_door open];
53 NSLog(@"出屋");
54 [_door close];
55 }//进出方法
56 -(void)takeAbreath
57 {
58 // window = [[Window alloc] init ];
59 [_window open];
60 NSLog(@"进气");
61 NSLog(@"出气");
62 [_window close];
63 }//换气方法
64
65 @end
66 int main(int argc, const char * argv[])
67 {
68 @autoreleasepool
69 {
70 Housing *housing = [[Housing alloc] init];
71
72 housing .door = [[Door alloc] init];
73 housing .window = [[Window alloc] init ];
74 [housing InAndOut];
75 [housing takeAbreath];
76 housing.door.replace = @"红色";
77 [housing.door color];
78 }
79 return 0;
80 }
