View Controllers
INTRODUCTION TO UIKIT The Building Blocks of iOS Apps
WHAT IS UIKIT? Framework that helps us build Apps for iOS Provides default components Provides a skeleton of functionality within which we write our application code Main Components: Views and View Controllers which are used to build Scenes
APPS CONSIST OF SCENES
Login
Main
Settings
AND TRANSITIONS BETWEEN SCENES
Login
Main
Settings
SCENES
SCENES SimpleViewController UITextField
Scenes consist of View Controllers and Views UIView UIView
Views display information and can capture user input (Textfield, Button, ImageView) View Controllers are containers for views
UIButton
UIButton
VIEW CONTROLLERS
VIEW CONTROLLERS In most cases one Screen = one View Controller Each View Controller has one root View Different Views are added as subviews to the View of the View Controller A View Controller has no visual representation! You can only see the View of the View Controller
VIEW CONTROLLERS View Controllers manage Views Get informed about system events: •
View appears on screen
•
View disappears
•
Device rotates
VIEWS
VIEWS (Almost) anything that is visible on the iPhone’s screen is a View Views have a size and position, an appearance and can consume user input UIKit provides different View subclasses that represent different components: Image View, Text Fields, etc.
VIEW HIERARCHY
Every View can have other Views as Subviews Views are positioned relative to their parents
HOW DO VIEWS AND VIEW CONTROLLERS WORK TOGETHER?
MODEL VIEW CONTROLLER A View should only display content! A View Controller processes input, modifies/updates the View and communicates with the Model of your application
WHY MVC? Reusability of Views Consistency in Codebase by following convention of MVC Separation of Concerns (general OO principle), makes your codebase easier to understand and extend
VIEW EXAMPLE A UIView receives an object or a set of objects and displays them
UIUserAccountView Benji Developer [email protected] Contact
Delete
accountView.user = currentUser User
View can capture user input but should not perform any complex code, instead hand work off to View Controller
VIEW CONTROLLER EXAMPLE UIUserAccountViewController
UIUserAccountView Benji
ViewWillAppear
Developer [email protected] Download User Data
User Contact
iOS
contactUserPressed
presentEmailViewController
Delete
VIEW + CONTROLLER + MODEL UIUserAccountViewController
UIUserAccountView Benji
ViewWillAppear
Developer User
[email protected]
Download User Data Contact
iOS
contactUserPressed
presentEmailViewController
deleteButtonPressed
removeUser
updateUI
Remove UserAccountView
UserAcounts
removeUserById:
Delete
SUMMARY View and View Controller are the building blocks of iOS Apps View Controllers have no appearance, but they have a root View Every View can have subviews -> View Hierarchy Views should not contain any application logic View Controllers connect Views to the application logic / model
VIEW LIFECYCLE
VIEW LIFECYCLE ViewDidLoad initialize view properties here ViewWillAppear/ViewDidAppear Load data for your view ViewWillDisappear/ViewDidDisappear Clean up resources / perform save of edited data
SCENE TRANSITIONS
SCENE TRANSITIONS Transitions between scenes are called Segues Segues can be defined in Storyboard Segues can be triggered by actions or manually in code View Controllers can perform code when segues occur
CONTAINER VIEW CONTROLLERS
CONTAINER VIEW CONTROLLERS Most transitions between Scenes happen within a Container View Controller Most apps have at least one Container View Controller
CONTAINER VIEW CONTROLLERS
UINavigationViewController UITabBarController
SUMMARY Apps consist of multiple Scenes Multiple Scenes are contained in a Container View Controller We transition between Scenes using Segues Scenes consist of View Controllers and Views
ADDITIONAL RESOURCES View Controller Programming Guide https://developer.apple.com/library/ios/featuredarticles/viewcontrollerpgforiphoneos/ View Programming Guide https://developer.apple.com/library/ios/documentation/windowsviews/conceptual/ viewpg_iphoneos/
WHAT IS UIKIT? Framework that helps us build Apps for iOS Provides default components Provides a skeleton of functionality within which we write our application code Main Components: Views and View Controllers which are used to build Scenes
APPS CONSIST OF SCENES
Login
Main
Settings
AND TRANSITIONS BETWEEN SCENES
Login
Main
Settings
SCENES
SCENES SimpleViewController UITextField
Scenes consist of View Controllers and Views UIView UIView
Views display information and can capture user input (Textfield, Button, ImageView) View Controllers are containers for views
UIButton
UIButton
VIEW CONTROLLERS
VIEW CONTROLLERS In most cases one Screen = one View Controller Each View Controller has one root View Different Views are added as subviews to the View of the View Controller A View Controller has no visual representation! You can only see the View of the View Controller
VIEW CONTROLLERS View Controllers manage Views Get informed about system events: •
View appears on screen
•
View disappears
•
Device rotates
VIEWS
VIEWS (Almost) anything that is visible on the iPhone’s screen is a View Views have a size and position, an appearance and can consume user input UIKit provides different View subclasses that represent different components: Image View, Text Fields, etc.
VIEW HIERARCHY
Every View can have other Views as Subviews Views are positioned relative to their parents
HOW DO VIEWS AND VIEW CONTROLLERS WORK TOGETHER?
MODEL VIEW CONTROLLER A View should only display content! A View Controller processes input, modifies/updates the View and communicates with the Model of your application
WHY MVC? Reusability of Views Consistency in Codebase by following convention of MVC Separation of Concerns (general OO principle), makes your codebase easier to understand and extend
VIEW EXAMPLE A UIView receives an object or a set of objects and displays them
UIUserAccountView Benji Developer [email protected] Contact
Delete
accountView.user = currentUser User
View can capture user input but should not perform any complex code, instead hand work off to View Controller
VIEW CONTROLLER EXAMPLE UIUserAccountViewController
UIUserAccountView Benji
ViewWillAppear
Developer [email protected] Download User Data
User Contact
iOS
contactUserPressed
presentEmailViewController
Delete
VIEW + CONTROLLER + MODEL UIUserAccountViewController
UIUserAccountView Benji
ViewWillAppear
Developer User
[email protected]
Download User Data Contact
iOS
contactUserPressed
presentEmailViewController
deleteButtonPressed
removeUser
updateUI
Remove UserAccountView
UserAcounts
removeUserById:
Delete
SUMMARY View and View Controller are the building blocks of iOS Apps View Controllers have no appearance, but they have a root View Every View can have subviews -> View Hierarchy Views should not contain any application logic View Controllers connect Views to the application logic / model
VIEW LIFECYCLE
VIEW LIFECYCLE ViewDidLoad initialize view properties here ViewWillAppear/ViewDidAppear Load data for your view ViewWillDisappear/ViewDidDisappear Clean up resources / perform save of edited data
SCENE TRANSITIONS
SCENE TRANSITIONS Transitions between scenes are called Segues Segues can be defined in Storyboard Segues can be triggered by actions or manually in code View Controllers can perform code when segues occur
CONTAINER VIEW CONTROLLERS
CONTAINER VIEW CONTROLLERS Most transitions between Scenes happen within a Container View Controller Most apps have at least one Container View Controller
CONTAINER VIEW CONTROLLERS
UINavigationViewController UITabBarController
SUMMARY Apps consist of multiple Scenes Multiple Scenes are contained in a Container View Controller We transition between Scenes using Segues Scenes consist of View Controllers and Views
ADDITIONAL RESOURCES View Controller Programming Guide https://developer.apple.com/library/ios/featuredarticles/viewcontrollerpgforiphoneos/ View Programming Guide https://developer.apple.com/library/ios/documentation/windowsviews/conceptual/ viewpg_iphoneos/
