利用正则表达式解析URL

-(NSString *) jiexi:(NSString *)CS webaddress:(NSString *)webaddress
{
     NSError *error;
     NSString *regTags=[[NSString alloc] initWithFormat:@"(^|&|\?)+%@=+([^&]*)(&|$)",CS];
    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:regTags
                                                                          options:NSRegularExpressionCaseInsensitive
                                                                            error:&error];
    
    // 执行匹配的过程
   // NSString *webaddress=@"http://wgpc.wzsafety.gov.cn/dd/adb.htm?adc=e12&xx=lkw&dalsjd=12";
    NSArray *matches = [regex matchesInString:webaddress
                                      options:0
                                        range:NSMakeRange(0, [webaddress length])];
    for (NSTextCheckingResult *match in matches) {
        //NSRange matchRange = [match range];
        //NSString *tagString = [webaddress substringWithRange:matchRange];  // 整个匹配串
//        NSRange r1 = [match rangeAtIndex:1];
//        if (!NSEqualRanges(r1, NSMakeRange(NSNotFound, 0))) {    // 由时分组1可能没有找到相应的匹配，用这种办法来判断
//            //NSString *tagName = [webaddress substringWithRange:r1];  // 分组1所对应的串
//            return @"";
//        }
        
        NSString *tagValue = [webaddress substringWithRange:[match rangeAtIndex:2]];  // 分组2所对应的串
        //    NSLog(@"分组2所对应的串:%@
",tagValue);
        return tagValue;
    }
    return @"";
}