Observable#propertyDidChange()

Notify the observer system that a property has just changed.

Sometimes you need to change a value directly or indirectly without actually calling get() or set() on it. In this case, you can use this method and propertyWillChange() instead. Calling these two methods together will notify all observers that the property has potentially changed value.

Note that you must always call propertyWillChange and propertyDidChange as a pair. If you do not, it may get the property change groups out of order and cause notifications to be delivered more often than you would like.