When to use invoke and begininvoke in wpf

Invoke is Synchronous whereas BeginInvoke is Asynchronous, which means in case of Invoke, control will not

return to the calling object until the callback returns. If you are OK with blocking calls, then you can choose Invoke.

create one simple app add 
one textbox and enter some text and add two buttons and see how threads are working.

public MainWindow()  
{  InitializeComponent();  txt.Text = "HI";  
}  
private void invoke_Click(object sender, RoutedEventArgs e)  
{  string enteredText = "";    txt.Dispatcher.Invoke(new Action(() => enteredText = txt.Text), null);  MessageBox.Show(enteredText);  
}  
private void begininvoke_Click(object sender, RoutedEventArgs e)  
{  string enteredText = "";    txt.Dispatcher.BeginInvoke(new Action(() => enteredText = txt.Text), null);  MessageBox.Show(enteredText);  
}