Parse xml file line by line and modify lines

Hi, Here's the job. Parse an xml file which contains a program tv guide (xmltv format).Here is a sample but the real file is 25Mb. Create a new xml file with : - only the channels desired (up to 30 channels) : function keepchannel([login to view URL], [login to view URL], ...) ; - new GMT time : function changeTime(channel, oldtime, newtime), exemple changeTime([login to view URL],+0100,-1000); - new channel name, function changeChannelName(oldname, newname); -> modify the value of tag <display-name> - new channel id, function changeChannelID(oldname, newname); That's all. The program must be written in objective c. I need the source code with comments. Watch UTF8, I need the accents. I don't need any dialog box, I'll just modify the source myself