standford cs 193p: 04-model view controller

8/14/2019 Standford CS 193P: 04-Model View Controller

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CS193P - Lecture 4

iPhone Application Development

Application LifecycleModel, View, ControllerNib FilesControls and Target-Action


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Announcements

No more NDA Yay!

Class website and materials will remain publicly accessible

Still planning to set up university team

Enables on-device development Enables students to build apps and distribute them


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Todays Topics

HelloPoly demo

Application Lifecycle

Model, View, Controller design

Interface Builder and Nib Files

Controls and Target-Action


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HelloPoly Demo


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Application Lifecycle


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What makes an app tick?

Anatomy of an application Compiled code

Your code

Cocoa Touch framework code

Nib files Contains user interface elements (along with other objects)

Includes details about object relationships

Resources (sounds, images, etc)

Info.plist file (application configuration)

How do all the pieces fit together?


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App Lifecycle

Launcha

pp

Loadm

ainnib

Waitf

orevent

Hand

leevent

Exitapp

Appin

itialized


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UIKit Framework

UIKit drives the show, youre just along for the ride

Every application has a single instance of UIApplication Singleton design pattern

@interface UIApplication

+ (UIApplication *)sharedApplication@end

Orchestrates the lifecycle of an application

Dispatches events

Manages status bar, application icon badge

Rarely subclassed

Uses delegation instead


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Delegation

Control passed to delegate objects to perform application-specific behavior

Avoids need to subclass complex objects

Many UIKit classes use delegates

UIApplication UITableView

UITextField


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Xcode project templates have one set up by default

Object you provide that participates in application lifecycle

Can implement various methods which UIApplication will call

Examples:

UIApplicationDelegate


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Examples:

- (void)applicationDidFinishLaunching:(UIApplication *)application;

- (void)applicationWillTerminate:(UIApplication *)application;



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Examples:

- (void)applicationDidReceiveMemoryWarning:(UIApplication *)application;

- (void)applicationWillResignActive:(UIApplication *)application;

- (BOOL)application:(UIApplication *)application handleOpenURL:(NSURL *)url;

- (void)applicationDidFinishLaunching:(UIApplication *)application;

- (void)applicationWillTerminate:(UIApplication *)application;



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Info.plist file

A property list containing various pieces of application-specificinformation Status bar style (default, black, hidden)

If your application is a landscape application

Whether app icon has prerendered shine and bevel Whether your app uses wifi for communication

If your application is iPhone only (non-iPod touch)

Application icon

Can edit most pieces of information using interface in Xcode Project > Edit Active Target Foo menu item

On the properties tab


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Working with the frameworks

UIKit provides lots of functionality

UIKit and you Dont fight the frameworks

Understand the designs and how you fit into them


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Model, View, Controller

If you take nothing else away from this class...


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HelloPoly

This weeks assignment is a full MVC application

Next weeks assignment will flesh it out further

It is not designed to be a complex application rather, provide a series of small studies of the fundamentals of a

Cocoa Touch application


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Divides an application into 3 main functional pieces


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Model Manages the app data and state, not concerned with UI or

presentation

Often persists somewhere

View Displays the model objects to the user

Allows user to manipulate data by responding to events


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Model Manages the app data and state, not concerned with UI or

presentation

Often persists somewhere

View Displays the model objects to the user

Allows user to manipulate data by responding to events

Controller Coordinates the model and the view, keeps the view updated

when model changes, etc. Typically where app logic is.


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HelloPoly


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PolygonShape

HelloPoly


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PolygonShape UIKit controlsPolygonView (next week)

HelloPoly


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PolygonShape

Controller

UIKit controlsPolygonView (next week)

HelloPoly


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increaseButton

numberOfSidesLabel


HelloPoly

PolygonShape

Controller

decreaseButton

increase

decrease

polygonShape


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increaseButton

numberOfSidesLabel


HelloPoly

PolygonShape

Controller

decreaseButton

increase

decrease

polygonShape


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increaseButton

numberOfSidesLabel


HelloPoly

PolygonShape

Controller

decreaseButton

increase

decrease

polygonShape


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HelloPoly


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Interface Builder and Nib Files


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Nib Files - Design time

At design time in IB, you layout user interface elements

add controller objects

define connections between controller and UI

When saved, objects are archived Standardized archiving / serialization mechanism

NSCoding

Archives and Serialization Programming Guide


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Nib Loading

At runtime, objects are unarchived Objects have same values/settings as in Interface Builder

Ensures all outlets and actions are connected

Order of unarchiving is not defined

If loading the nib automatically creates objects and order isundefined, how do I customize? For example, restore previous polygon information


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-awakeFromNib

Control point to implement any additional logic after nibloading

You often implement it in your controller class e.g. to restore previously saved application state

Guaranteed everything has been unarchived from nib, and allconnections are made before -awakeFromNib is called

- (void)awakeFromNib {

// do customization here

}


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Controls and Target-Action


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increaseButton

numberOfSidesLabel


HelloPolyController

decreaseButton

increase

decrease

polygonShape

PolygonShape


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increaseButton

numberOfSidesLabel


HelloPolyController

decreaseButton

increase

decrease

polygonShape


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Controls - Events

View objects that allows users to initiate some type of action Respond to variety of events

Touch events

touchDown

touchDragged (entered, exited, drag inside, drag outside) touchUp (inside, outside)

Value changed

Editing events

editing began

editing changed

editing ended


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Controls - Target/Action

When event occurs, action is invoked on target object

Controller


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target: myObject

action: @selector(decrease)

event: UIControlEventTouchUpInside

Controller


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target: myObject



Controller


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target: myObject



Controller


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UIControlEventTouchUpInside

target: myObject



Controller


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UIControlEventTouchUpInside

-(void)decrease

target: myObject



Controller


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Action Methods

3 different flavors of action method selector types- (void)actionMethod;

- (void)actionMethod:(id)sender;

- (void)actionMethod:(id)sender withEvent:(UIEvent *)event;

UIEvent contains details about the event that took place


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Action Method Variations

- (void)increase {

// bump the number of sides of the polygon up

polygon.numberOfSides += 1;

}

// for example, if control is a slider...

- (void)adjustNumberOfSides:(id)sender {

polygon.numberOfSides = [sender value];}

Simple no-argument selector

Single argument selector - control is sender


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Action Method Variations

- (void)adjustNumberOfSides:(id)sender

withEvent:(UIEvent *)event

{

// could inspect event object if you needed to

}

Simple no-argument selector


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Multiple target-actions

Controls can trigger multiple actions on different targets inresponse to the same event Different than Cocoa on the desktop where only one target-

action is supported


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Manual Target-Action

@interface UIControl

- (void)addTarget:(id)target action:(SEL)actionforControlEvents:(UIControlEvents)controlEvents;

- (void)removeTarget:(id)target action:(SEL)action

forControlEvents:(UIControlEvents)controlEvents;

@end

Same information IB would use API and UIControlEvents found in UIControl.h

UIControlEvents is a bitmask


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Questions?

standford cs 193p: 04-model view controller

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