IsolatedStorageFileStream.BeginRead Method

Begins an asynchronous read.

Namespace:  System.IO.IsolatedStorage
Assembly:  mscorlib (in mscorlib.dll)


Public Overrides Function BeginRead ( _
    buffer As Byte(), _
    offset As Integer, _
    numBytes As Integer, _
    userCallback As AsyncCallback, _
    stateObject As Object _
) As IAsyncResult
public override IAsyncResult BeginRead(
    byte[] buffer,
    int offset,
    int numBytes,
    AsyncCallback userCallback,
    Object stateObject


  • buffer
    Type: array<System.Byte[]
    The buffer to read data into.
  • offset
    Type: System.Int32
    The byte offset in buffer at which to begin reading.
  • numBytes
    Type: System.Int32
    The maximum number of bytes to read.
  • userCallback
    Type: System.AsyncCallback
    The method to call when the asynchronous read operation is completed. This parameter is optional.
  • stateObject
    Type: System.Object
    The status of the asynchronous read.

Return Value

Type: System.IAsyncResult
An IAsyncResult object that represents the asynchronous read, which is possibly still pending. This IAsyncResult must be passed to this stream's EndRead method to determine how many bytes were read. This can be done either by the same code that called BeginRead or in a callback passed to BeginRead.


Exception Condition

The isolated store has been removed.


Isolated storage is disabled.


The buffer length minus offset is less than numBytes.


buffer is nulla null reference (Nothing in Visual Basic).


offset or numBytes is negative.


An asynchronous read was attempted past the end of the file.


The stream has been disposed.


The current position in the stream is updated when you issue the asynchronous read or write, not when the I/O operation completes.

You must call EndRead with this IAsyncResult to find out how many bytes were read.

Version Notes

Silverlight for Windows Phone Silverlight for Windows Phone

 When this method is called within a Windows Phone application, the operation is executed synchronously. If you have to read a large amount of data and do not want to interrupt the UI thread, you can create a new thread and perform the operation on that thread.

Version Information


Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0


For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.