第二十四讲：Objective-C内存管理之拷贝简述

Sian

1、创建一个字符串NSString，创建一个可变字符串NSMutableString；
2、分别使用copy与mutableCopy方法分别对NSString与NSMutableString类型对象进行赋值
3、效果是NSString copy后为NSString、NSString mutableCopy后为MutableString、NSMutableString copy后为NSString无法使用appendString方法、NSMutableString mutableCopy后为NSMutableString；
main.m

1. //
2. //  main.m
3. //  Copy
4. //
5. //  Created by yusian on 14-1-22.
6. //  Copyright (c) 2014年 yusian. All rights reserved.
7. //
9. #import <Foundation/Foundation.h>
11. int main(int argc, const char * argv[])
12. {
14.     @autoreleasepool {
15.         
16.         NSString * s1 = [[NSString alloc] initWithString:@"String"];
17.         NSMutableString * s2 = [[NSMutableString alloc] initWithString:@"MutableString"];
18.         NSString * s11 = [s1 copy];
19.         NSString * s12 = [s1 mutableCopy];
20.         NSMutableString * s21 = [s2 copy];
21.         NSMutableString * s22 = [s2 mutableCopy];
22.         [s12 appendString:@" to mutableString"];
23.         //[s21 appendString:@" to String"];
24.         [s22 appendString:@" to mutableString"];
25.         NSLog(@"s1 is "%@"", s1);
26.         NSLog(@"s2 is "%@"", s2);
27.         NSLog(@"s11 is "%@" copy to:"%@"",s1, s11);
28.         NSLog(@"s12 is "%@" mutableCopy to:"%@"",s1, s12);//NSString may not respond to 'appendString:
29.         NSLog(@"s21 is "%@" copy to ,Can't use [s21 appendString:]",s21);
30.         NSLog(@"s22 is "%@" mutableCopy to:"%@"",s2, s22);
31.         [s1 release];
32.         [s2 release];
33.         
34.         
35.     }
36.     return 0;
37. }

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运行结果：

1. 2014-01-22 19:12:35.398 Copy[1254:303] s1 is "String"
2. 2014-01-22 19:12:35.399 Copy[1254:303] s2 is "MutableString"
3. 2014-01-22 19:12:35.399 Copy[1254:303] s11 is "String" copy to:"String"
4. 2014-01-22 19:12:35.400 Copy[1254:303] s12 is "String" mutableCopy to:"String to mutableString"
5. 2014-01-22 19:12:35.400 Copy[1254:303] s21 is "MutableString" copy to ,Can't use [s21 appendString:]
6. 2014-01-22 19:12:35.400 Copy[1254:303] s22 is "MutableString" mutableCopy to:"MutableString to mutableString"
7. Program ended with exit code: 0

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