Asynchronously writes a sequence of bytes to the current stream and advances the current position within this stream by the number of bytes written.
The Stream.WriteAsync(Byte, int, int) method enables you to perform resource-intensive I/O operations without blocking the main thread. This performance consideration is particularly important in a win8_appname_long app or desktop_appname app where a time-consuming stream operation can block the UI thread and make your app appear as if it is not working. The async methods are used in conjunction with the async and await keywords in Visual Basic and C#.
Use the Stream.CanWrite property to determine whether the current instance supports writing.