當(dāng)前位置：
首頁 >
Objective-C：MRC(引用计数器)在OC内部的可变对象是适用的，不可变对象是不适用的(例如 NSString、NSArray等)...
發(fā)布時(shí)間：2025/6/17
39
豆豆
生活随笔
收集整理的這篇文章主要介紹了
Objective-C：MRC(引用计数器)在OC内部的可变对象是适用的，不可变对象是不适用的(例如 NSString、NSArray等)...
小編覺得挺不錯(cuò)的,現(xiàn)在分享給大家,幫大家做個(gè)參考.
引用計(jì)數(shù)和字符串 內(nèi)存中的常量字符串的空間分配與其他對(duì)象不同，他們沒有引用計(jì)數(shù)機(jī)制 凡是自定義的對(duì)象都有引用計(jì)數(shù)機(jī)制； OC內(nèi)部中對(duì)象分為可變對(duì)象(NSMutableString等)和不可變對(duì)象(NSString、NSArray等)， 不可變對(duì)象不適用于引用計(jì)數(shù)的機(jī)制,可變的對(duì)象適用引用計(jì)數(shù)機(jī)制。 ?? ?? 1 // main.m
2 // 03-unmutableobject
3 //
4 // Created by ma c on 15/8/13.
5 // Copyright (c) 2015年. All rights reserved.
6 //
7
8 #import <Foundation/Foundation.h>
9
10 int main(int argc, const char * argv[])
11 {
12 @autoreleasepool
13 {
14 //不可變對(duì)象不適用于引用計(jì)數(shù)
15 //1.創(chuàng)建3個(gè)對(duì)象
16 NSString *str1 = @"hello world";//不可變對(duì)象
17
18 NSString *str2 = [NSString stringWithString:@"how arer you"];//不可變對(duì)象
19
20 NSMutableString *str3 = [NSMutableString stringWithString:@"I am fine"];//可變對(duì)象
21
22 NSLog(@"str1 = %lu,str2 = %lu,str3 = %lu",[str1 retainCount],[str2 retainCount],[str3 retainCount]);
23
24
25 //2.將3個(gè)對(duì)象添加到可變數(shù)組中
26 NSMutableArray *array = [NSMutableArray array];
27 [array addObject:str1];
28 [array addObject:str2];
29 [array addObject:str3];
30 NSLog(@"str1 = %lu,str2 = %lu,str3 = %lu",[str1 retainCount],[str2 retainCount],[str3 retainCount]);
31
32
33 //3.對(duì)3個(gè)對(duì)象做retain操作
34 [str1 retain];
35 [str2 retain];
36 [str3 retain];
37 NSLog(@"str1 = %lu,str2 = %lu,str3 = %lu",[str1 retainCount],[str2 retainCount],[str3 retainCount]);
38
39 //4.將3個(gè)對(duì)象從數(shù)組中刪除
40 [array removeObject:str1];
41 [array removeObject:str2];
42 [array removeObject:str3];
43 NSLog(@"str1 = %lu,str2 = %lu,str3 = %lu",[str1 retainCount],[str2 retainCount],[str3 retainCount]);
44
45 //5.對(duì)對(duì)象做release操作---對(duì)應(yīng)上面的retain操作
46 [str1 release];
47 [str2 release];
48 [str3 release];
49 NSLog(@"str1 = %lu,str2 = %lu,str3 = %lu",[str1 retainCount],[str2 retainCount],[str3 retainCount]);
50
51
52 //6.對(duì)對(duì)象做release操作---對(duì)應(yīng)上面的對(duì)象創(chuàng)建操作(避免內(nèi)存泄露)
53 [str1 release];
54 [str2 release];
55 [str3 release];
56 }
57 return 0;
58 }
??
測(cè)試結(jié)果是：
2015-08-13 17:41:26.569 03-unmutableobject[1622:105614] str1 = 18446744073709551615,str2 = 18446744073709551615,str3 = 1 2015-08-13 17:41:26.570 03-unmutableobject[1622:105614] str1 = 18446744073709551615,str2 = 18446744073709551615,str3 = 2 2015-08-13 17:41:26.571 03-unmutableobject[1622:105614] str1 = 18446744073709551615,str2 = 18446744073709551615,str3 = 3 2015-08-13 17:41:26.571 03-unmutableobject[1622:105614] str1 = 18446744073709551615,str2 = 18446744073709551615,str3 = 2 2015-08-13 17:41:26.571 03-unmutableobject[1622:105614] str1 = 18446744073709551615,str2 = 18446744073709551615,str3 = 1 Program ended with exit code: 0?
說明：可以明顯看出，NSString是不適用引用計(jì)數(shù)機(jī)制的。
轉(zhuǎn)載于:https://www.cnblogs.com/XYQ-208910/p/4728026.html
總結(jié)
以上是生活随笔為你收集整理的Objective-C：MRC(引用计数器)在OC内部的可变对象是适用的，不可变对象是不适用的(例如 NSString、NSArray等)...的全部?jī)?nèi)容，希望文章能夠幫你解決所遇到的問題。
- 上一篇： 线程学习笔记（一）
- 下一篇： OC中protocol、category