CheckBox myCheckBox = new CheckBox(); myCheckBox.IsChecked = true; myCheckBox.SetValue(CheckBox.IsCheckedProperty, false);
foreach (CheckBox checkbox in myStackPanel.Children) { checkbox.SetValue(CheckBox.IsCheckedProperty, true); }Here, we have a StackPanel control containing multiple CheckBox controls. We loop through each Checkbox using a foreach loop and use the SetValue method to set each one's value to true (checked). The package library for this method would be the System.Windows.Controls package, part of the .NET Framework.