Book.h:

#import <Foundation/Foundation.h>  @interface Book : NSObject @property float price; -(id)initeWithPrice:(float)price; @end

Book.m:

#import "Book.h"  @implementation Book #pragma mark 构造方法 -(id)initeWithPrice:(float)price {     if(self=[super init])     {         _price=price;     }     return self; } #pragma mark 回收方法 -(void)dealloc{     NSLog(@"Book:%f 被销毁了",_price);      [super dealloc]; } @end

Student.h:

#import <Cocoa/Cocoa.h> @class Book;  @interface Student : NSObject {     Book * _book; } @property int age; -(id)initWithAge:(int)age; @property Book * book; -(void)readBook; @end

Student.m:

#import "Student.h" #import "Book.h"  @implementation Student #pragma mark - 生命周期方法 -(id)initWithAge:(int)age{     if(self=[super init])     {         _age=age;      }     return self; } -(void)dealloc {     [_book release];     NSLog(@"Student: %i被销毁了",_age);     [super dealloc]; }  //如果手动设置getter和setter方法 Xcode就不会帮我们自动生成synthesize，也就不会自动生成带下划线的属性 #pragma mark - 设置getter和setter方法 #pragma mark setter方法 -(void)setBook:(Book *)book {     if(_book!=book)     {     //先释放旧对象，再retain新对象     [_book release];//OC里面没有空指针释放错误 [nil release]不报错     //book：1     _book=[book retain];     }  } #pragma mark getter方法 -(Book *)book{     return _book; } #pragma mark - 公共方法 #pragma mark 读书 -(void)readBook{     NSLog(@"当前读的书的价格是：%f",_book.price); } #pragma mark - 私有方法 #pragma mark 私有方法1 -(void)test1{      } #pragma mark 私有方法2 -(void)test2{  } #pragma mark 私有方法3 -(void)test3{  } @end

main:

#import <Foundation/Foundation.h> #import "Student.h" #import "Book.h"  void test(Student * stu){     //book:1     Book * book=[[Book alloc] initeWithPrice:11.2];     //book:2     stu.book=book;     //book:1     [book release];      Book * book1=[[Book alloc] initeWithPrice:22.2];     stu.book=book1;     [book1 release]; } void test1(Student *stu) {     [stu readBook]; } int main(int argc, const char * argv[]) {      @autoreleasepool {  //        Student *stu=[[[Student alloc] initWithAge:10] autorelease]; //        NSLog(@"Student age is %i",stu.age); //        Book *book=[[Book alloc] initeWithPrice:11.1f]; //        NSLog(@"Book price is %.1f",book.price); // //        stu.book=book; //        NSLog(@"%@",stu.book); //        [book release];         //计数器         //stu 1                  Student *stu=[[Student alloc] initWithAge:10];         //book:1         //stu:1         test(stu);         //book:1         //stu:1         test1(stu);         //stu:0         //book:0         [stu release];  //在释放stu时候也释放book，因为stu在setter的时候retain了一下，就由它释放          Student * stu1=[[[Student new]initWithAge:20] autorelease];         test(stu1);      }     return 0; }
结果：

2013-08-02 15:01:11.571 内存管理2 a对象之间的内存管理[832:303] Book:11.200000 被销毁了

2013-08-02 15:01:11.573 内存管理2 a对象之间的内存管理[832:303] 当前读的书的价格是：22.200001

2013-08-02 15:01:11.573 内存管理2 a对象之间的内存管理[832:303] Book:22.200001 被销毁了

2013-08-02 15:01:11.574 内存管理2 a对象之间的内存管理[832:303] Student: 10被销毁了

2013-08-02 15:01:11.574 内存管理2 a对象之间的内存管理[832:303] Book:11.200000 被销毁了

2013-08-02 15:01:11.574 内存管理2 a对象之间的内存管理[832:303] Book:22.200001 被销毁了

2013-08-02 15:01:11.575 内存管理2 a对象之间的内存管理[832:303] Student: 20被销毁了