12 - iOS MVC

MVC

• Program is divided into 3 logical units
  • Controller
  • Model
  • View

Communication

• Communication management is the key

• Controlles can communicate with their Model
• Controlles can communicate with their Model and View
• Model and View should never speak to each other!!!!

• Can View communicate vith Controller?
  • Communication is blind and structured. Controller can specify a target on itself and hand out an action to the View.
    View sends the action when events happen in UI

All together

• Sometimes View needs to synchronize with the Controller.
  • Will, should, did, …. (willScroll, shouldScroll, didScroll)
• Controller sets itself as the View’s delegate.
  • Delegate is set via protocol.
• Views do not own the data they display.
  • If needed, they have a protocol to acquire it.
  • Controllers are almost always that data source (not Model).
  • Controllers interpret/format Model information for View.
• Can the Model talk directly to the Controller?
  • No, they are UI independent. But sometimes Model (network) needs to inform, that data has changed.
  • Broadcast (messaging) mechanism is used for this. Interested parties can subscribe to these messages (Controllers and Models).