iOS Question How can I save a displayed image in a webview?

Sub [B]WebView1_PageFinished[/B] (Url As String)
If grabpic Then
Timer1.Initialize("Pause",4000) '2.5 seconds
Timer1.Enabled=True
End If
grabpic = False
End Sub
Sub [B]Pause_Tick[/B]
Timer1.Enabled=False
Try
Dim btmp As Bitmap = WebView1.CaptureBitmap
Dim Out As OutputStream
Out = File.OpenOutput(TargetDir, "map.png", False)
btmp.WriteToStream(Out, 100, "PNG")
Out.Close
Button3.visible = True
Catch
Log(LastException)
End Try
End Sub