字符串排序和characterAtIndex:i 方法-优快云博客

本文链接：https://blog.youkuaiyun.com/ios_xumin/article/details/72764614

本文介绍了如何使用Objective-C处理Unicode字符，包括遍历字符串中的每个Unicode字符并进行格式化输出的方法。此外，还详细展示了如何构建HTTP请求，包括设置请求URL、参数构造及加密过程。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

haracterAtIndex:i 这个方法的作用是
 返回索引i 所在UniCode 字符    而不是字串
所以应该是
unichar strxmlchar=[strcs characterAtIndex:i];

接收字符
并且format要以%C（大写字母C）的形式

    NSString *strcs=@"猜猜看";
    NSString *str=@"";
    for(int i=0;i<strcs.length;i++){
        unichar strxmlchar=[strcs characterAtIndex:i];
        str=[NSStringstringWithFormat:@"%C",strxmlchar];
        NSLog(@"%C",strxmlchar);
    }

为你推荐的另一种方法
for(int i=0;i<strcs.length;i++){

        str=[strcs substringWithRange:NSMakeRange(i, 1)];
        NSLog(@"%@",str);
        if ([str isEqualToString:@"看"]) {
            NSLog(@"%@是指定字符",str);
        }
    }

//订单类---拼接request Url
- (NSMutableURLRequest *)requestWithOrderMethod:(NSString *)method andPara:(NSString *)para
{
    NSString *stringUrl = [NSString stringWithFormat:@"%@/%@",kOrderURL,method];
    NSString *encodeStr = [stringUrl stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
    NSURL *url = [NSURL URLWithString:encodeStr];
    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:30.0f];
    [request setHTTPMethod:@"POST"];
    DLog(@"订单请求Url = %@",url);
    //application/x-www-form-urlencoded
    //    [request setValue:@"text/html; charset=utf-8" forHTTPHeaderField:@"Content-Type"];
    [request setHTTPBody:[[self requestBodyWithMethod:method parameters:para] dataUsingEncoding:NSUTF8StringEncoding]];
    return request;
}
 
 
  
  

 
 
//构造参数
- (NSString *)requestBodyWithMethod:(NSString *)method parameters:(NSString *)parameters
{
    NSString * gStr = nil;
    if(parameters.length != 0)
    {
        gStr = [NSString stringWithFormat:@"%@&UserName=%d&sign=%@",parameters,111111,[self signKey:parameters method:method]];
    }
    else
    {
        gStr = [NSString stringWithFormat:@"UserName=%d&sign=%@",111111,[self signKey:parameters method:method]];
    }
        DLog(@"构造参数str = %@",gStr);
    return gStr;
}

//后台定的加密规则
- (NSString*)signKey:(NSString *)params method:(NSString *)method
{
    NSMutableString *paramMustr = [NSMutableString string];
    NSString *sKey ;
    NSString *result ;
    if(params.length != 0)
    {
        NSMutableArray *paramsMuArr = [[NSMutableArray alloc] init];
        for (int i = 0; i<params.length; i++)
        {
            unichar c = [params characterAtIndex:i];
            NSString * cStr = [NSString stringWithCharacters:&c length:1];
            [paramsMuArr addObject:cStr];
        }
        
        NSArray *paramsArr = [paramsMuArr sortedArrayUsingSelector:@selector(compare:)];
        
        for (int j = 0; j<[paramsArr count]; j++)
        {
            [paramMustr appendString:paramsArr[j]];
        }
        //    NSLog(@"排序 = %@",paramMustr);
        
        //拼接
        sKey = [NSString stringWithFormat:@"%@%@%@%@%@",@"111111",@"111111",method,@"111111",paramMustr];
        //MD5加密
        result = [sKey md5Hash];
    }
    else
    {
        //拼接
        sKey = [NSString stringWithFormat:@"%@%@%@%@",@"111111",@"111111",method,@"111111"];
        //MD5加密
        result = [sKey md5Hash];
    }
    
    return  result;
}