内存管理

 

 

#import <Foundation/Foundation.h>

//.txt

//.data

//.bss

//.heap

//.stack

//引用计数

//count = 10

//count --;

//count = 0

 

int main(int argc, const char * argv[]) {

    @autoreleasepool {

        char *pstr = malloc(1000);

        char *pstr1 = pstr;

        char *pstr2 = pstr;

        

        scanf("%s", pstr);

        printf("%s\n", pstr);

        free(pstr);

        pstr = NULL;

    }

    return 0;

}

 

 

 ————————————————————————————————————分割————————————————————————————

#import <Foundation/Foundation.h>

 

@interface Dog : NSObject

 

@end

 

 

#import "Dog.h"

 

@implementation Dog

 

- (void)dealloc

{

    NSLog(@"对象被释放");

    [super dealloc];

}

 

@end

 

 

 

 

#import <Foundation/Foundation.h>

#import "Dog.h"

//ARC  automatic reference counting //自动引用计数

//MRC  manaul reference counting  //手动引用计数

 

//对于引用计数来说，有一套内存管理的黄金法则:

//The basic rule to apply is everything that increases the reference counter with alloc, [mutable]copy[withZone:] or retain is in charge of the corresponding [auto]release.

//如果对一个对象使用了alloc、[mutable]copy、retain，那么你必须使用相应的release或者autorelease。

//通俗一点的说法就是谁污染谁治理，谁杀的谁埋。

 

 

int main(int argc, const char * argv[]) {

    @autoreleasepool {

        Dog *xiaoHei = [[Dog alloc] init];

        //[xiaoHei release];//release 计数器-1 自动调用dealloc

    }

    NSLog(@"程序退出");

    return 0;

}

 

 

 

 ————————————————————————————————————分割————————————————————————————

#import <Foundation/Foundation.h>

 

@interface Dog : NSObject

 

@end

 

#import "Dog.h"

 

@implementation Dog

 

@end

 

 

 

//对于引用计数来说，有一套内存管理的黄金法则:

//The basic rule to apply is everything that increases the reference counter with alloc, [mutable]copy[withZone:] or retain is in charge of the corresponding [auto]release.

//如果对一个对象使用了alloc、[mutable]copy、retain，那么你必须使用相应的release或者autorelease。

//通俗一点的说法就是谁污染谁治理，谁杀的谁埋。

 

//创建一个对象, 对应的引用计数 retainCount

 

#import <Foundation/Foundation.h>

#import "Dog.h"

 

int main(int argc, const char * argv[]) {

    @autoreleasepool {

        Dog *xiaoHei = [[Dog alloc] init];

        NSLog(@"xiaoHei = %ld", xiaoHei.retainCount);//获取引用计数值

        //retain : 引用计数进项保留(增加对对象的拥有权), 引用计数加1

        Dog *xiaoBai = [xiaoHei retain];

        NSLog(@"xiaoBai = %ld", xiaoBai.retainCount);

        

        Dog *xiaoHua = [xiaoHei retain];

        NSLog(@"xiaoHua = %ld", xiaoHua.retainCount);

        

        [xiaoHei release];//使引用计数减1

        xiaoHei = nil;

        

        NSLog(@"retainCount = %ld", xiaoBai.retainCount);

        [xiaoBai release];

        NSLog(@"retainCount = %ld", xiaoHua.retainCount);

        [xiaoHua release];//dealloc

        

        xiaoHua = nil;

        

        NSLog(@"今天天气不错, 是出游的日子");

        NSLog(@"今天天气不错, 是出游的日子");

        NSLog(@"今天天气不错, 是出游的日子");

        NSLog(@"今天天气不错, 是出游的日子");

        NSLog(@"今天天气不错, 是出游的日子");

        NSLog(@"今天天气不错, 是出游的日子");

        NSLog(@"今天天气不错, 是出游的日子");

        NSLog(@"今天天气不错, 是出游的日子");

        NSLog(@"今天天气不错, 是出游的日子");

        sleep(1);

        

 

        //NSLog(@"retainCount = %ld", xiaoHua.retainCount);//当一个对象被释放后, 不应该再给它发送消息

    }

    return 0;

}

 

 

 

 

 ————————————————————————————————————分割————————————————————————————

#import <Foundation/Foundation.h>

#import "Dog.h"

 

@interface Person : NSObject

{

    Dog *_dog;

}

 

- (void)setDog:(Dog *)newDog;

 

- (Dog *)dog;

 

- (void)dealloc;

 

@end

 

 

#import "Person.h"

 

@implementation Person

 

//写法一 不OK

//- (void)setDog:(Dog *)dog

//{

//    _dog = dog;

//}

//写法二

//- (void)setDog:(Dog *)dog

//{

//    _dog = [dog retain];

//}

 

//写法三

//- (void)setDog:(Dog *)dog

//{

//    [_dog release];

//    _dog = [dog retain];

//}

 

//标准写法

 

- (void)setDog:(Dog *)dog

{

    if (_dog!=dog) {

        [_dog release];

        _dog =[dog retain];

    }

}

 

- (Dog *)dog

{

    return _dog;

}

 

- (void)dealloc

{

    NSLog(@"dog dealloc");

    [super dealloc];

}

@end

 

 

 

 

#import <Foundation/Foundation.h>

 

@interface Dog : NSObject

 

@end

 

 

 

#import "Dog.h"

 

@implementation Dog

 

@end

 

 

#import <Foundation/Foundation.h>

#import "Dog.h"

#import "Person.h"

 

int main(int argc, const char * argv[]) {

    @autoreleasepool {

        //写法一

        //xiaohei 被释放, 那么per.dog被释放

//        Dog *xiaoHei = [[Dog alloc] init];

//        Person *per = [[Person alloc] init];

//        per.dog = xiaoHei;

//        

//        [xiaoHei release];

//        

//        [per release];

        //写法二, 如果人再持有别的狗，就会造成第一条狗得不到释放，内存泄露

//        Dog *xiaoHei = [[Dog alloc] init];

//        Dog *xiaoBai = [[Dog alloc] init];

//        

//        Person *per = [[Person alloc] init];

//        per.dog = xiaoHei ;

//        NSLog(@"count = %ld", xiaoHei.retainCount);

//        [xiaoHei release];//count =1;

//        per.dog = xiaoBai;

//        

//        [xiaoBai release];

//        [per release];

        

        //写法三

        //如果本来持有一条狗，又重新设置这条狗，先进行release，这个时候，很可能dog就销毁了，然后，就没法再次retain了

//        Dog *xiaoHei = [[Dog alloc] init];

//        Dog *xiaoBai = xiaoHei;

//        Person *per = [[Person alloc] init];

//        per.dog = xiaoHei;

//        per.dog = xiaoBai;

 

    }

    return 0;

}

 

 ————————————————————————————————————分割————————————————————————————

 

#import <Foundation/Foundation.h>

#import "Dog.h"

 

@interface Person : NSObject

{

    NSString *_name;

    int _age;

    Dog *_dog;

}

 

//assign 直接赋值  int float long long long (基本数据类型)

//@property (nonatomic, assign) Dog *dog;

@property (nonatomic, assign)int age;

@property (nonatomic, retain)Dog *dog;

@property (nonatomic, copy)NSString *name;

 

@end

 

 

 

#import "Person.h"

 

@implementation Person

 

//assgin

- (void)setAge:(int)age

{

    _age = age;

}

 

//retain (自定类 类定义的变量)

 

- (void)setDog:(Dog *)dog

{

    if (_dog!=dog) {

        [_dog release];

        _dog =[dog retain];

    }

}

 

//copy NSString NSArray NSDirctionary

 

- (void)setName:(NSString *)name

{

    if (_name != name) {

        [_name release];

        _name = [name copy];

    }

}

 

 

@end

 

 

 

 

#import <Foundation/Foundation.h>

 

@interface Dog : NSObject

 

@end

 

 

 

#import "Dog.h"

 

@implementation Dog

 

@end

 

 

#import <Foundation/Foundation.h>

#import "Dog.h"

#import "Person.h"

 

int main(int argc, const char * argv[]) {

    @autoreleasepool {

        //NSString *str= @"xiaoHei";

        //NSMutableString *str= [NSMutableString stringWithFormat:@"xiaoHei"];

        char *pstr = malloc(100); 

        strcpy(pstr, "xiaoHei");

        NSString *str = [NSString stringWithUTF8String:pstr];

        

        //NSString *str = [NSString stringWithFormat:@"%@",str];

        

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

        per.name = str;

        

        NSLog(@"str = %p", str);

        NSLog(@"name = %p", per.name);

    }

    return 0;

}

 

 

 

 ————————————————————————————————————分割————————————————————————————

#import <Foundation/Foundation.h>

 

//copy

//mutableCopy

 

int main(int argc, const char * argv[]) {

    @autoreleasepool {

        /*

        //copy

        //copy 把可变对象或者不可变对象, 拷贝生成不可变对象

        

        NSString *str = @"helloworld";

        NSMutableString *mulStr = [NSMutableString stringWithString:str];

        

        id obj1 = [str copy];

        

        id obj2 = [mulStr copy];

        

        //NSLog(@"str = %p", str);

        //NSLog(@"obj = %p", obj1);

        

        NSLog(@"mulStr = %p", mulStr);

        NSLog(@"obj2 = %p", obj2);

        

        NSLog(@"obj2 = %@", obj2);

        

        //[obj appendString:@"zhongguo"];

        //[obj2 appendString:@"zhongguo"] ;

        

        

        

        //NSLog(@"%@", obj);

        

        //[obj release];

        [obj2 release];

        */

        //multableCopy

        //把可变对象或者不可变对象, 拷贝生成可变对象

        

        NSString *str = @"qiangfeng";

        NSMutableString *mulStr = [NSMutableString stringWithString:str];

        

        id obj = [str mutableCopy];

        

        id obj2 = [mulStr mutableCopy];

        

        NSLog(@"%@", obj);

        NSLog(@"obj2 = %@", obj2);

        

        [obj appendString:@"helloworld"];

        NSLog(@"%@", obj);

        [obj2 appendString:@"1000phone"];

        NSLog(@"obj2 = %@", obj2);

        

    }

    return 0;

}

 

 ————————————————————————————————————分割————————————————————————————

 

#import <Foundation/Foundation.h>

 

int main(int argc, const char * argv[]) {

    @autoreleasepool {

        //字符串内存管理, retainCount 的值不定, 只管遵守内存管理法则

        

        NSString *str = @"qianfeng";//常量区

        NSLog(@"str = %ld", str.retainCount);

        

        NSString *str1 = [[NSString alloc] initWithString:str];

        

        NSLog(@"%p %p", str, str1);

        

        NSLog(@"str1 = %ld", str1.retainCount);

        

        NSString *str2 = [[NSString alloc] initWithFormat:@"%@,%d", str, 12345];

        //str2 对象存储在堆中

        NSLog(@"str2 = %ld", str2.retainCount);

        

        NSString *str3 = [str retain];

        NSLog(@"str3 = %ld", str3.retainCount);

        

        NSString *str4 = [str1 retain];

        NSLog(@"str4 = %ld", str4.retainCount);

        

        NSString *str5 = [str2 retain];

        NSLog(@"str5 = %ld", str5.retainCount);

        

        NSMutableString *str6 = [[NSMutableString alloc] initWithString:str];

        NSLog(@"str6 = %ld", str6.retainCount);

        

        NSMutableString *str7 = [str6 retain];

        NSLog(@"str7 = %ld", str7.retainCount);

        

        [str1 release];

        [str2 release];

        [str3 release];

        [str4 release];

        [str5 release];

        [str6 release];

        [str7 release];

        

    }

    return 0;

}

 

 ————————————————————————————————————分割————————————————————————————

#import <Foundation/Foundation.h>

 

@interface Dog : NSObject

 

@end

 

 

 

#import "Dog.h"

 

@implementation Dog

 

@end

 

 

 

#import <Foundation/Foundation.h>

#import "Dog.h"

 

//数组

 

int main(int argc, const char * argv[]) {

    @autoreleasepool {

        Dog *xiaoHei = [[Dog alloc] init];

        Dog *xiaoBai = [[Dog alloc] init];

        Dog *xiaoHua = [[Dog alloc] init];

        Dog *xiaoHuang = [[Dog alloc] init];

        

        NSLog(@"xiaoHei = %ld", xiaoHei.retainCount);

        NSLog(@"xiaoBai = %ld", xiaoBai.retainCount);

        NSLog(@"xiaoHua = %ld", xiaoHua.retainCount);

        NSLog(@"xiaoHuang = %ld", xiaoHuang.retainCount);

        

        NSMutableArray *arr = [[NSMutableArray alloc] initWithObjects:xiaoBai,xiaoHei,xiaoHua,xiaoHuang, nil];

        NSLog(@"xiaoHei = %ld", xiaoHei.retainCount);

        NSLog(@"xiaoBai = %ld", xiaoBai.retainCount);

        NSLog(@"xiaoHua = %ld", xiaoHua.retainCount);

        NSLog(@"xiaoHuang = %ld", xiaoHuang.retainCount);

        

        [arr addObject:xiaoBai];

         NSLog(@"xiaoBai = %ld", xiaoBai.retainCount);

        [arr addObject:xiaoBai];

        NSLog(@"xiaoBai = %ld", xiaoBai.retainCount);

        //当往数组中添加对象, 对应的对象的引用计数加1

        

        NSLog(@"len = %ld", [arr count]);

        [xiaoBai release];

        [xiaoHei release];

        [xiaoHua release];

        [xiaoHuang release];

        

        NSLog(@"xiaoHei = %ld", xiaoHei.retainCount);

        NSLog(@"xiaoBai = %ld", xiaoBai.retainCount);

        NSLog(@"xiaoHua = %ld", xiaoHua.retainCount);

        NSLog(@"xiaoHuang = %ld", xiaoHuang.retainCount);

        [arr release];//把数组中的每个元素,引用计数减1

        

        //NSLog(@"xiaoHei = %ld", xiaoHei.retainCount);

        //NSLog(@"xiaoBai = %ld", xiaoBai.retainCount);

        //NSLog(@"xiaoHua = %ld", xiaoHua.retainCount);

        //NSLog(@"xiaoHuang = %ld", xiaoHuang.retainCount);

        

        

    }

    return 0;

}

 

 ————————————————————————————————————分割————————————————————————————

#import <Foundation/Foundation.h>

 

@interface Dog : NSObject

 

@end

 

 

 

#import "Dog.h"

 

@implementation Dog

 

@end

 

 

#import <Foundation/Foundation.h>

#import "Dog.h"

 

//autorelease autoreleasepool

int main(int argc, const char * argv[]) {

    @autoreleasepool {//自动释放池

        

        Dog *xiaoHei = [[Dog alloc] init];

        

        //[xiaoHei release];

        [xiaoHei autorelease];//把xiaoHei的拥有权给自动释放池, 自动池帮我们释放对象内存

        //自动释放池类似数组,自动释放池把其中的每个对象都release一次

        NSLog(@"count = %ld", xiaoHei.retainCount);

        

    }

    @autoreleasepool {

 

    }    

    @autoreleasepool {

 

    }

    return 0;

}

 

 ————————————————————————————————————分割————————————————————————————

#import <Foundation/Foundation.h>

 

@interface Dog : NSObject

 

+(Dog *)DogCreat;

 

@end

 

 

 

#import "Dog.h"

 

@implementation Dog

 

//在类方法里面也要遵守内存管理法则

+ (Dog *)DogCreat

{

    Dog *dog = [[self alloc] init];

    //[dog release]; 不能调用

    [dog autorelease];

    

    return dog;

}

 

@end

 

 

#import <Foundation/Foundation.h>

#import "Dog.h"

 

int main(int argc, const char * argv[]) {

    @autoreleasepool {

        

        Dog *dog = [Dog DogCreat];

        

        

        

    }

    return 0;

}