多对象的内存管理

 1>当你想占有某个对象时，就应该让对象的引用计数器+1（让对象做一次retain操作）

 2>当你不占有某个对象时，让对象的引用计数器-1(让对象做一次release操作)

 3>谁retain,谁release

 4>谁alloc,谁release

 5>当引用计数为0 ，就会调用对象的dealloc

 6>[super dealloc];写到最后

 

 1 #import <Foundation/Foundation.h>
 2 #import "Book.h"
 3 #import "Person.h"
 4 int main(int argc, const char * argv[]) {
 5     
 6 //  当引用计数为0 ，就会调用对象的dealloc
 7     
 8 //    b=1  b=1
 9     Book *b = [[Book alloc]init];
10 //    p1=1   p1=1
11     Person *p1 = [[Person alloc]init];
12 //    p1占有了
13 //   p1 =1,b=2     p1 =1,b=2
14     [p1 setBook:b];
15 //    [b retain];
16 //   alloc +1,retain+1
17 //    p1 =0,b=0   p1=0 ,b=1
18     [p1 release];
19 //     b=1  b=0
20     [b release];
21 //    b = nil;
22 //    [b release];
23     
24     return 0;
25 }
main
 1 #import <Foundation/Foundation.h>
 2 
 3 @interface Book : NSObject
 4 {
 5 
 6     int _price;
 7     
 8 }
 9 //@property int price;
10 
11 - (void)setPrice:(int)price;
12 - (int)price;
13 @end
Book.h
 1 @implementation Book
 2 
 3 - (void)setPrice:(int)price{
 4 
 5     _price = price;
 6 
 7 }
 8 - (int)price{
 9 
10     return _price;
11 
12 }
13 
14 - (void)dealloc{
15 
16     NSLog(@"BOOK对象被销毁");
17     [super dealloc];
18 
19 }
20 @end
Book.m
 1 #import <Foundation/Foundation.h>
 2 #import "Book.h"
 3 @interface Person : NSObject
 4 {
 5 
 6     Book *_book;
 7 
 8 }
 9 
10 - (void)setBook:(Book *)book;
11 - (Book *)book;
12 @end
Person.h
 1 #import "Person.h"
 2 
 3 @implementation Person
 4 
 5 - (void)setBook:(Book *)book{
 6 //    _book = book;
 7     _book =[book retain];
 8 
 9 }
10 - (Book *)book{
11 
12     return _book;
13 
14 }
15 
16 - (void)dealloc{
17     
18     [_book release];  //  人类被销毁，Book也被销毁
19     NSLog(@"Person对象被销毁");
20     [super dealloc];
21     
22 }
23 @end
Person.m

 _____________________________________________________set方法的内存管理 _____________________________________________________

 

 内存管理代码：

 1>只要调用了alloc就必须要有release(autorelease)

 对象不是通过alloc产生的，就不要release

 2>set代码规范：基本数据类型直接赋值

 3>dealloc代码规范：一定要调用[super dealloc]并且当前一定要对象所拥有的对象做一次release

 

 1 #import <Foundation/Foundation.h>
 2 #import "Car.h"
 3 #import "Person.h"
 4 int main(int argc, const char * argv[]) {
 5     Person *p = [[Person alloc]init];
 6     Car *c1 = [[Car alloc]init];
 7     c1.speed = 100;
 8     p.age = 18;
 9 //    p拥有c1
10    
11 //    僵尸对象，当某个对象的计数器为0，对它retain是不对的，防止错误：在set方法中加一个判断
12     p.car = c1;
13 //    p.car = c1;
14 //    p.car = c1;
15 //     [c1 release];
16     [c1 release];
17     Car *c2 = [[Car alloc]init];
18     c2.speed = 200;
19     p.car = c2;
20     
21     [c2 release];
22     [p release];
23     return 0;
24 }
main
 1 #import <Foundation/Foundation.h>
 2 #import "Car.h"
 3 @interface Person : NSObject
 4 {
 5 
 6     Car *_car;
 7     int _age;
 8 }
 9 
10 - (void)setCar:(Car *)car;
11 - (int)car;
12 
13 - (void)setAge:(int)age;
14 - (int)age;
15 @end
Person.h
 1 #import "Person.h"
 2 
 3 @implementation Person
 4 - (void)setCar:(Car *)car{
 5     if (car !=_car){  //  判断传入的值是不是原来那个
 6 //        对旧车做一次release
 7     [_car release];
 8 //        对新车做一次retain
 9     _car = [car retain];
10 
11     }
12 //    _car = [car retain];
13 }
14 - (int)car{
15 
16     return _car;
17 
18 }
19 
20 
21 - (void)setAge:(int)age{
22 //   基本数据类型直接赋值
23     _age = age;
24 
25 }
26 - (int)age{
27 
28     return _age;
29 
30 }
31 - (void)dealloc{
32 NSLog(@"person对象呗销毁了");
33     [_car release];
34     
35     [super dealloc];
36 
37 }
38 @end
Person.m
 1 #import <Foundation/Foundation.h>
 2 
 3 @interface Car : NSObject
 4 {
 5 
 6     int _speed;
 7 
 8 }
 9 - (void)setSpeed:(int)speed;
10 - (int)speed;
11 @end
Car.h
 1 #import "Car.h"
 2 
 3 @implementation Car
 4 - (void)setSpeed:(int)speed{
 5 
 6     _speed = speed;
 7 }
 8 - (int)speed{
 9 
10     return _speed;
11 
12 }
13 - (void)dealloc{
14 //   self->_speed  直接访问成员变量
15 //    _speed       直接访问成员变量
16 //    [self speed] get方法
17 //    self.speed   get方法
18     NSLog(@"速度为%d的Car对象被销毁了",_speed);
19     [super dealloc];
20 }
21 @end
car.m

 

 

 

 

 

 

 

 

posted @ 2018-03-20 10:06  懒猫口米  阅读(130)  评论(0)  编辑  收藏  举报