Home / Objective-C patterns
- model is the data. gives the data to view. view reads the data. controller changes data
- view is the display. reads data from model. reports user interaction to controller
- controller changes the data based on user interaction in the view
- in cocoa, this is how responding to actions from controls is implemented
- e.g. when button is pressed, framework sends a message to application code
- general way in which object (e.g. button) can send messages to undetermined object (part of application code you write)
- IB (Interface Builder) does that when you create new control, class and instance and ctrl-drag defines target action
- messages send to Holder object are forwarded to Delegate
- Holder needs an instance of Delegate and a way to set it
Chain of responsibility:
- a message is handled by the most appropriate object out of many
- used in cocoa for handling events. An event message is sent to a first responder object (e.g. if clicked on a button, button objects is the first responder). If the object doesn’t know how to handle the message, it sends it to the next object in chain etc.
Go to index of articles.