RadioButton not showing as "Checked" when bound value is true - xaml

Question

In my project I am setting a bool property as true when constructing my ViewModel.
In the View, I have a RadioButton which is bound to the value of this property. The first time I open the View, the RadioButton is "checked" (perfect, exactly what I want!).
However, if I close and then re-open the View, the RadioButton is not "checked", despite the bound property having a value of 'true'. In my constructor I am setting 'StaggeredMode' to true, but the setter is being called three times (firstly, value = true; secondly, value = false; thirdly, value = true)
Any help will be appreciated!
XAML:
<RadioButton GroupName="AppointmentStart"
Content="Staggered"
IsChecked="{Binding StaggeredMode, Mode=TwoWay}"
VerticalAlignment="Top"
HorizontalAlignment="Left"
Margin="310,247,0,0" />
C#:
private bool staggeredMode;
public bool StaggeredMode
{
get { return staggeredMode; }
set { staggeredMode = value; }
}

Answer 1

Your StaggeredMode property should be observable so the view can be notified about property changes from your ViewModel.
You can implement INotifyPropertyChanged by yourself or use one of existing implementations like this, this or this.
Here is a basic implementation of INotifyPropertyChanged interface:
public abstract class ObservableObject : INotifyPropertyChanged
{
public virtual void RaisePropertyChanged(string propertyName)
{
OnPropertyChanged(propertyName);
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
PropertyChangedEventHandler handler = this.PropertyChanged;
if (handler != null)
{
var e = new PropertyChangedEventArgs(propertyName);
handler(this, e);
}
}
}
Then you derive your ViewModel from ObservableObject and raise OnPropertyChanged event every time your property value has been changed:
public class MyViewModel : ObservableObject
{
...
private bool staggeredMode;
public bool StaggeredMode
{
get { return staggeredMode; }
set
{
staggeredMode = value;
OnPropertyChanged("StaggeredMode");
}
}
...
}