在Windows Phone 8.1 RT的弱模式下监听属性更改事件

Question

我有以下对象：

public class EventCounter : INotifyPropertyChanged
{
    private int _count = 0;
    public int Count {
        get
        {
            return _count;
        }
        set
        {
            _count = value;
            NotifyPropertyChanged("Count");
        }
    }


    public event PropertyChangedEventHandler PropertyChanged;

    public void NotifyPropertyChanged(string propertyName)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this,
                new PropertyChangedEventArgs(propertyName));
        }
    }
}

我希望每次使用＆＃34;弱事件模式更改计数值时都会收到通知＆＃34;

我该怎么做？