Your URL variable contains the url address of the location of the XML file you want to download.
However you are applying NSWindowsCP1252StringEncoding to the url, not to the content of the file.
xmlData is nil because dataWithContentsOfURL: cannot find the file at the location you have specified within URL.
You need to download the file first, then once its downloaded then you can be concerned about what encoding its in and how to parse it.
The way you are using NSWindowsCP1252StringEncoding has got nothing to do with the content of the file.