通过参数名获取URL里拼接的参数

-(NSString*)getParamByName:(NSString*)name URLString:(NSString*)url{
    NSError*error;
    NSString*regTags=[[NSString alloc]initWithFormat:@"(^|&|\\?)+%@=+([^&]*)(&|$)",name];
    NSRegularExpression*regex=[NSRegularExpression regularExpressionWithPattern:regTags options:NSRegularExpressionCaseInsensitive error:&error];
    // 执行匹配的过程
    NSArray*matches=[regex matchesInString:url options:0 range:NSMakeRange(0,[url length])];
    for(NSTextCheckingResult*match in matches){
        NSString*tagValue=[url substringWithRange:[match rangeAtIndex:2]];// 分组2所对应的串
        return tagValue;
    }
    return @"";
}