反向查找指定字符

 NSString* Str = [NSString stringWithFormat:@"http://www.cnmjw.com.cn/AppServerTwo/building/getDYLBuildingList2?uuid=%@&option=%@",uuid,cid];
    NSRange range =[Str rangeOfString:@"/" options:NSBackwardsSearch];
    NSString *currentURL;
    if (range.length>0) {
      currentURL  = [Str substringFromIndex:range.location];
    }