Save a Collection of objects to disk Windows 10 Universal App - vb.net

Question

I have a collection of objects which also contain collections, and I would like to save them to a file and read later. This is Windows 10 UNIVERSAL app .net 4.5 and in VB
I've this, but it gives the error "Synchronous operations should not be performed on the UI thread. Consider wrapping this method in Task.Run."}
Public Sub SaveSpRules(FileName As String)
Dim fs As New FileStream(FileName, FileMode.OpenOrCreate)
Dim serializer As New XmlSerializer(GetType(Rule))
Dim writer As New StreamWriter(fs)
serializer.Serialize(writer, r)
End Sub
Rule is class and the collection is called SpecialRulesCollection, this code does compile but doesn't work
Any help is gratefully received. PLEASE note this for Windows 10 Universal app, I can't get BinaryWriter to compile as this isn't include in the Universal app.

Answer 1

Thanks Oyiwai I found the answer
Public Async Sub SaveSpRules(FileName As String, t As Object)
Dim myfile As StorageFile
myfile = Await ApplicationData.Current.LocalFolder.CreateFileAsync("test.dat", CreationCollisionOption.ReplaceExisting)
Dim KnownTypeList As New List(Of Type)
KnownTypeList.Add(GetType(Rules))
KnownTypeList.Add(GetType(Rule))
Dim r As Streams.IRandomAccessStream
r = Await myfile.OpenAsync(FileAccessMode.ReadWrite)
Using outStream As Streams.IOutputStream = r.GetOutputStreamAt(0)
Dim serializer As New DataContractSerializer(GetType(Rules), KnownTypeList)
serializer.WriteObject(outStream.AsStreamForWrite(), t)
Await outStream.FlushAsync()
outStream.Dispose()
r.Dispose()
End Using
End Sub
Public Async Sub ReadFile()
Dim t As New Collection(Of Rule)
Dim myfile As Stream
Dim r As New Rules
Dim KnownTypeList As New List(Of Type)
KnownTypeList.Add(GetType(Rules))
Dim serializer As New DataContractSerializer(GetType(Rules), KnownTypeList)
myfile = Await ApplicationData.Current.LocalFolder.OpenStreamForReadAsync("test.dat")
r = serializer.ReadObject(myfile)
End Sub