How do I read XML on iOS?

I have a xml in ProjectFolder/Assets/ but I can't load it on iOS. Output windows print that file can't be found. I have tried different scripts to get file path but neither work, for example:

 public static string GetiPhoneDocumentsPath () 
         { 
                 string path = Application.dataPath.Substring (0, Application.dataPath.Length - 5); 
                 path = path.Substring(0, path.LastIndexOf('/'));  
                 return path + "/Documents"; 
         }
 //-----------------------------------------------------------------------------

 string fileNameBase = Application.dataPath.Substring(0, Application.dataPath.LastIndexOf('/'));
 fileName = fileNameBase.Substring(0, fileNameBase.LastIndexOf('/')) + "/Documents/" + FILE_NAME;

 //-----------------------------------------------------------------------------

 string fileName = Application.persistentDataPath + "/" + FILE_NAME;

 //-----------------------------------------------------------------------------

 Path.Combine( Application.persistentDataPath, FILE_NAME);

So... what am I doing wrong? Do I have to change some settings in Unity Editor? Where do I have to put the xml file? How do I load a xml file on iPhone/iPad?