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2.4.2.2.1 MVC.md

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MVC-N(network)

  1. Model View Controller (MVC)
  2. MVC CS193P Stanford iOS

Those who encounter Massive View Controller problems should switch to Model-View-Controller. The only pattern that Apple promotes for the development of its applications.

MVC:

  • Model/Domains - What your application is, but not how it's displayed
  • Controller - How your Model is presented to the user. (UI Logic). More properly, Controllers interpret/format the Model's information for the View.
  • View - The controller's "minions". Typically very generic elements. It is important to note that views do not own the data they display.

MVC is about managing the communications between these different types. The keys are:

alt text

  • The controller can talk to both the model and the view directly.
  • The model and the view should NEVER talk to each other. They handle entirely different parts of the application
  • The view can talk to the controller, but the communication needs to be
    • "Blind" - The View elements are all generic, so they know nothing about how the app is intended to function.
    • Structured - The View needs to think in advance about how its going to communicate with the controller. For example:
      • The controller to drop a target on itself that the view can call, e.g. when a button is pressed.
      • The Controller can also set itself as the View's delegate. This is useful when the View needs to synchronise with the Controller, e.g. when scrolling down a page. The delegate is set using protocals. More on these later.
      • Views can also often use Controllers as a data source (remember that they do not own the data they display). This is another form of delegate, which is very similar, but has a slightly different set of methods.
  • The model cannot talk directly to the controller (because it is UI independent). However, it can broadcast messages (e.g. an update has happened on data item X) that he controller can subscribe to.

Interestingly, apps will often use a combination of MVCs, with each individual one responsible for one (or a related set of) UI screens.

When one MVC wants to talk to another, it always treat that MVC as one of its Views. It is important to restrict these connections, or debugging apps become impossible.

2.4.2.2 UI Pattern Theme Folder | Back To iOSWiki Contents | 2.4.2.2.2 MVVM Theme