黑马程序员22——OC之内存管理（多个对象之间的内存管理）

#import <Foundation/Foundation.h>

@interface Book : NSObject

{

    int _price;

}

- (void)setPrice:(int)price;

- (int)price;
@end

#import "Book.h"

@implementation Book

- (void)setPrice:(int)price

{

    _price = price;

}

- (int)price

{

    return _price;

}

- (void)dealloc

{

    NSLog(@"Book对象被回收");

    [super dealloc];

}

@end

#import <Foundation/Foundation.h>

#import "Book.h"

@interface Person : NSObject

{

    Book *_book;

}

- (void)setBook:(Book *)book;

- (Book *)book;

@end

#import "Person.h"

@implementation Person
- (void)setBook:(Book *)book

{

    _book = [book retain];

}

- (Book *)book

{

    return _book;

}

- (void)dealloc

{

    [_book release];

    NSLog(@"Person对象被回收");

    [super dealloc];

}

@end

/*

 1.你想使用（占用）某个对象，就应该让对象的计数器+1（让对象做一次retain操作）

 2.你不想再使用（占用）某个对象，就应该让对象的计数器-1（让对象做一次release）

 

 3.谁retain，谁release

 

 4.谁alloc，谁release

 */

#import <Foundation/Foundation.h>

#import "Person.h"

#import "Book.h"

int main()

{

    // b-1

    Book *b = [[Book alloc] init];

    // p-1

    Person *p1 = [[Person alloc] init];

    

    //p1想占用b这本书

    // b-2

    [p1 setBook:b];

    

    // p-0

    // b-1

    [p1 release];

    p1 = nil;

    

    // b-0

    [b release];

    b = nil;

    return 0;

}