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iOS Bootcamp: learning to create awesome apps on iOS using Swift (Lecture 04)
This document discusses the Model-View-Controller (MVC) design pattern and view controllers in iOS. It explains that MVC separates an app into three components: the model (data), the view (user interface), and the controller (logic). The controller manages the model and view, and allows them to communicate indirectly. View controllers are the main interface between views and models, and their lifecycle methods like viewDidLoad are described. Common iOS view controllers like UITabBarController and UINavigationController are also mentioned.
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iOS Bootcamp: learning to create awesome apps on iOS using Swift (Lecture 04)
- 1. IOS ESSENTIALS Lecture 04 JonathanR. Engelsma, Ph.D.
- 2. TOPICS • Model /View / Controller • Understanding ViewControllers and their life cycle. • Overview of commonly used iOSViewControllers
- 3. MODEL/VIEW/CONTROLLER Model Controller View Our iOS codeis broken up into 3 different components (Inspired by Paul Hegarty’s very excellent MVC lecture.)
- 4. MODEL/VIEW/CONTROLLER Controller View The MODEL isthe data our app produces/consumes. Model
- 5. MODEL/VIEW/CONTROLLER Model Controller The VIEW iswhat the user sees and interacts with on screen. View
- 6. MODEL/VIEW/CONTROLLER Model View The CONTROLLERmanages the model and the view. Controller
- 7. MODEL/VIEW/CONTROLLER Model Controller View Controller can manipulatethe model directly.
- 8. MODEL/VIEW/CONTROLLER Model Controller View Controller can manipulatethe view directly. Takes place via an “outlet”
- 9. MODEL/VIEW/CONTROLLER Model Controller View Model /View shouldNEVER talk directly to each other!
- 10. MODEL/VIEW/CONTROLLER Model Controller View Views can sortof talk to controller, but only in a very controlled manner! Controller defines an action. View is wired up to call action.
- 11. MODEL/VIEW/CONTROLLER Model Controller View Controller serves astheView’s delegate and data source via Protocols D elegate Data Source
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- 13. VIEW CONTROLLERS • Viewcontrollers manage a screen’s view hierarchy and the segues between view controllers. • The “glue” between views and models in MVC. • View controllers: • initialize and setup models • populate the view hierarchy with views • coordinate with the view hierarchy (delegate) • format data for the views (data source)
- 14. VIEW CONTROLLER LIFECYCLE • Recallthe methods generated when we created our first app: override func viewDidLoad() { super.viewDidLoad() // Do any additional setup after loading the view, typically from a nib. self.configureView() } override func didReceiveMemoryWarning() { super.didReceiveMemoryWarning() // Dispose of any resources that can be recreated. } • These are methods that help us coordinate with the controller’s lifecycle.
- 15. VIEW CONTROLLER LIFE CYCLE •Understanding the view controller life cycle allows us to properly manage the controller’s models and views. • Whenever a view controller’s view property is accessed a chain of events is triggered. https://developer.apple.com/library/IOS/featuredarticles/ViewControllerPGforiPhoneOS/ViewLoadingandUnloading/ViewLoadingandUnloading.html
- 16. View property Accessed View exists? loadView Return view loadView overriden? RunloadView Storyboard? Load from storyboard Empty View viewDidLoad Y Y Y N N N
- 17. VIEW CONTROLLER METHODS Method NameDescription viewDidLoad View has finished loading. viewWillAppear View is about to appear. viewDidAppear View just appeared. viewWillDisappear View is about to disappear. viewDidDisappear View just disappeared didRecieveMemoryWarning Low memory conditions detected.
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