您好,登录后才能下订单哦!
密码登录
登录注册
点击 登录注册 即表示同意《亿速云用户服务条款》
今天来学习一下Dealloc方法的使用。
它的作用是,当对象的引用计数为0,系统会自动调用dealloc方法,回收内存。它的一般写法:
1:-(void)dealloc{
[super dealloc]; }
2:-(void)dealloc{NSLog(@"laptop dead"); [_cpu release]; [super dealloc]; }(一):为什么需要调用父类的dealloc方法?
子类的某些对象实例是继承自父类的。因此,我们需要调用父类的dealloc方法,来释放父类
拥有的这些对象。
(二):调用的顺序
一般说调用的顺序是,当子类的对象释放完时,然后再释放父类的所拥有的实例。这一点与调用初始化方法,
正好相反
下面使用一个例子来演示一下:
1:父类Vehicle.h
#import <Foundation/Foundation.h> @interface Vehicle : NSObject { @private NSString *_name; } -(id)initWithName:(NSString *)name; @end2:父类Vehicle.m
#import "Vehicle.h"
@implementation Vehicle
-(id)initWithName:(NSString *)name{ self=[super init]; if(self){ _name=[name copy]; } return self; } -(void)dealloc{ NSLog(@"vehicle dead"); [_name release]; [super dealloc]; } @end3:子类Car.h#import <Foundation/Foundation.h> #import "Vehicle.h" @class Engine; @interface Car : Vehicle { Engine *_engine; } -(void)setEngine:(Engine *)engine; @end4:子类Car.m#import "Car.h"
@implementation Car
-(void)setEngine:(Engine *)engine{ if(_engine!=engine){ [_engine release]; _engine=[engine retain]; } } -(Engine *)engint{ return _engine; } -(void)dealloc{ NSLog(@"Car dead"); [_engine release]; [super dealloc]; } @end5:测试main.m代码#import <Foundation/Foundation.h> #import "Engine.h" #import "Car.h" int main(int argc, const char * argv[]) { @autoreleasepool { NSString *name=[[NSString alloc]initWithFormat:@"audi"]; Car *car=[[Car alloc]initWithName:name]; [name release]; Engine *v6=[[Engine alloc]init]; [car setEngine:v6]; [v6 release]; //do something [car release]; } return 0; }运行截图
免责声明:本站发布的内容(图片、视频和文字)以原创、转载和分享为主,文章观点不代表本网站立场,如果涉及侵权请联系站长邮箱:is@yisu.com进行举报,并提供相关证据,一经查实,将立刻删除涉嫌侵权内容。