1 #import <Foundation/Foundation.h>
 2 
 3 int main(int argc, const char * argv[])
 4 {
 5     @autoreleasepool
 6     {
 7         //可变字符串是字符串的子类
 8         NSMutableString *str = [[NSMutableString alloc] initWithCapacity:1];
 9         [str setString:@"Hello"];
10         
11         //1.追加字符串
12         [str appendString:@" World"];
13         NSLog(@"str = %@", str);
14         int a = 100;
15         [str appendFormat:@" a = %d", a];
16         NSLog(@"str = %@", str);
17         
18         //2.替换字符串
19         NSRange rang = [str rangeOfString:@"World"];
20         [str replaceCharactersInRange:rang withString:@"IOS"];
21         NSLog(@"str = %@", str);
22         
23         //3.插入字符串
24         [str insertString:@"AAA" atIndex:6];
25         NSLog(@"str = %@", str);
26         
27         //4.删除字符串
28         NSRange rang1 = [str rangeOfString:@"AIOS"];
29         [str deleteCharactersInRange:rang1];
30         NSLog(@"str = %@", str);
31     }
32     return 0;
33 }
1 2016-08-10 14:58:17.314 NSMutableString[1215:182470] str = Hello World
2 2016-08-10 14:58:17.315 NSMutableString[1215:182470] str = Hello World a = 100
3 2016-08-10 14:58:17.315 NSMutableString[1215:182470] str = Hello IOS a = 100
4 2016-08-10 14:58:17.315 NSMutableString[1215:182470] str = Hello AAAIOS a = 100
5 2016-08-10 14:58:17.316 NSMutableString[1215:182470] str = Hello AA a = 100
6 Program ended with exit code: 0