1、 方式一

- (NSString *)reversalString:(NSString *)originString{
    NSString *resultStr = @"";
    for (NSInteger i = originString.length -1; i >= 0; i--) {
      NSString *indexStr = [originString substringWithRange:NSMakeRange(i, 1)];
      resultStr = [resultStr stringByAppendingString:indexStr];
    }
  return resultStr;
}

2、方式二

void char_reverse(char *cha){
  char *begin = cha;
  char *end = cha + strlen(cha) - 1;
  while (begin <= end) {
    char temp = *end;
    *(end--) = *begin;
    *(begin++) = temp;
  }
}
// 調(diào)用
  char cha[] = "hello,world";
  char_reverse(cha);
  printf("%s",cha);
  結(jié)果：dlrow,olleh