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:%@\n",tagValue);
return tagValue;
}
return @"";
}