FileStream + BinaryFormatter from C# to iOS doesn't work?

I'm trying to serialze an object using FileStream and BinaryFormatter technique. It works quite well on Android but on iOS it shows up the error. I've been rumblin with this problem for a week now read bunch of documentation and examples and tried to implement that all but nothing seems to work. I'm afraid this is beyond the scope of my current programing ability.

The error I get in XCode is following

Runned UnityEngine.Debug:Internal_Log(Int32, String, Object) UnityEngine.Debug:Log(Object) TestStore:Update()

(Filename: /Applications/buildAgent/work/d3d49558e4d408f4/artifacts/iPhonePlayer-armv7Generated/UnityEngineDebug.cpp Line: 53)

UnauthorizedAccessException: Access to the path "/var/mobile/Applications/A622D2E1-7364-48AD-91A4-053BA88A97C7/DocumentsTestSejva.svj" is denied. at System.IO.FileStream..ctor (System.String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, Boolean anonymous, FileOptions options) [0x00000] in :0 at System.IO.FileStream..ctor (System.String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize) [0x00000] in :0 at System.IO.File.Create (System.String path, Int32 bufferSize) [0x00000] in :0 at System.IO.File.Create (System.String path) [0x00000] in :0 at TestStore.SaveDataAndroid () [0x00000] in :0 at TestStore.Update () [0x00000] in :0

(Filename: Line: -1)

I'm guessing that the either FileStream or BinaryFormatter class is not compatibile with iOS. I have an application that is on store and is using same techinque which I made last year and it worked although I was saving data to a text file rather than serializing object because it was just some options parameters. Now I have to serialize class because data on this game I'm developing is quite more complex. Formerly I've used hardcoded pathing but now as I've read im using Application.persistantDataPath and also I've seen that due to reflection and something aobut FileStream doing at runtime which is not compatible with iOS, that I need to set some environment variable like this which I also did.

 void Awake()
     {
         if (Application.platform == RuntimePlatform.IPhonePlayer)
         {
             System.Environment.SetEnvironmentVariable("MONO_REFLECTION_SERIALIZER", "yes");
         } 
     }

If anyone can help me with this problem it would be most appreciated.

Thank you in advance

EDIT: Adding methods for saving and reading data: public void SaveData() { if (!File.Exists(Application.persistentDataPath + "/TestSejva.svj")) File.Create(Application.persistentDataPath + "/TestSejva.svj");

         FileStream fs = new FileStream(Application.persistentDataPath + "TestSejva.svj", FileMode.Truncate, FileAccess.Write, FileShare.ReadWrite);
         BinaryFormatter bf = new BinaryFormatter();
 
         Sranje sr = new Sranje();
         sr.FillObject(Random.Range(5, 15));
 
         try
         {
             bf.Serialize(fs, sr);
             Label1.text = "Data saved";
         }
         catch (System.Exception e)
         {
             Label1.text = e.ToString();
         }
 
         fs.Close();
         fs.Dispose();
     }

 public void LoadData()
     {
         FileStream fs = new FileStream(Application.persistentDataPath + "/TestSejva.svj", FileMode.Open, FileAccess.Read, FileShare.None);
         BinaryFormatter bf = new BinaryFormatter();
 
         Sranje sr = (Sranje)bf.Deserialize(fs);
         fs.Close();
 
         string rez = "";
 
         for (int i = 0; i < sr.Randomi.Length; i++)
         {
             rez += sr.Randomi[i].ToString();
         }
         rez += (" " + sr.Bla);
 
         Label1.text = rez;
     }