1 #import 
     
       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 World2 2016-08-10 14:58:17.315 NSMutableString[1215:182470] str = Hello World a = 1003 2016-08-10 14:58:17.315 NSMutableString[1215:182470] str = Hello IOS a = 1004 2016-08-10 14:58:17.315 NSMutableString[1215:182470] str = Hello AAAIOS a = 1005 2016-08-10 14:58:17.316 NSMutableString[1215:182470] str = Hello AA a = 1006 Program ended with exit code: 0