CS193P - Lecture 6 potx

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CS193P - Lecture 6

iPhone Application Development

Designing iPhone Applications

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Announcements

¢ Assignment 3 is due tomorrow at 11:59pm

= Questions?

¢ Presence 1 is due next Tuesday (4/28) ¢ Friday's optional section

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Announcements

¢ Online resources for auditors and iTunes U viewers

- http://groups.google.com/group/iphone-appdev-auditors - http://cs193p.com

- Not affiliated with Stanford or Apple

- Dont forget http://devforums.apple.com

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Announcements

¢ Many requests for us to post assignment solutions online = Short answer: We're lazy

- Longer answer: There are parts of the course that we reuse from

quarter to quarter, so we won't be distributing solutions - Discussing assignments is fine

: If you're a Stanford student, remember the Honor Code

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Today's Topics

¢ Designing iPhone Applications

¢ Model-View-Controller (Why and How?) ¢ View Controllers

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Organizing Content

"=> _ - ' locuson your user s data

a he, - One thing at a time

Jj!/10| *° Screenfuls of content

rê | b

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Patterns for Organizing Content

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Carrier John Appleseed Kate Bell Anna Haro Daniel Higgins Jr David Taylor Hank M Zakroff A Screenful of Content

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Parts of a Screenful

John Appleseed

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Parts of a Screenful

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Model-View-Controller

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Why Model-View-Controller?

¢ Ever used the word “spaghetti” to describe code?

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Why Model-View-Controller?

¢ Separating responsibilites also leads to reusability

¢ By minimizing dependencies, you can take a model or view class you've already written and use it elsewhere

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Communication and MVC

¢ How should objects communicate?

¢ Which objects know about one another?

Model

¢ Example: Polygon class

¢ Not aware of views or controllers

¢ Typically the most reusable

¢ Communicate generically using

= Key-value observing

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Communication and MVC

¢ How should objects communicate?

¢ Which objects know about one another?

View

¢ Example: PolygonView class

¢ Not aware of controllers, may be

aware of relevant model objects

¢ Also tends to be reusable

¢ Communicate with controller using

- larget-action

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Communication and MVC

¢ How should objects communicate?

¢ Which objects know about one another? Controller

¢ Knows about model and view objects ¢ The brains of the operation

¢ Manages relationships and data flow

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Communication and MVC

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Problem: Managing a Screenful

¢ Controller manages views, data and application logic ¢ Apps are made up of many of these

¢ Would be nice to have a well-defined starting point

- Ala UlView for views

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Problem: Building Typical Apps

¢ Some application flows are very common

- Navigation-based

: Tab bar-based

-, Combine the two

¢ Don't reinvent the wheel

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UIViewController

¢ Basic building block

¢ Manages a screenful of content

¢ Subclass to add your application logic

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“Your” and “Our” View Controllers

¢ Create your own UlViewController subclass for each screentul

¢ Plug them together using existing composite view controllers

ce

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“Your” and “Our” View Controllers

¢ Create your own UlViewController subclass for each screentul

¢ Plug them together using existing composite view controllers

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Your View Controller Subclass

#import <UIKit/UIKit.h>

@interface MyViewControLlLler : UIViewControLller { // A view controller will usually

// manage views and data NSMutabLeArray *myData; UILabel *myLabel;

b

// Expose some of its contents to clients @property Creadonly) NSArray *myData;

// And respond to actions

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The “View” in “View Controller”

¢ UlViewController superclass has a view property

- @property Cretain) UIView *view;

¢ Loads lazily

- On demand when requested

= Can be purged on demand as well (low memory)

¢ Sizing and positioning the view?

= Depends on where it’s being used

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When to call -loadView?

a DYo)ammelonie

¢ Cocoa tends to embrace a lazy philosophy

: Call -release instead of -dealloc

: Call -setNeedsDisplay instead of -drawRect:

¢ Allows work to be deferred or coalesced

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Creating Your View in Code

¢ Override -loadView

= Never call this directly

¢ Create your views

¢ Set the view property

¢ Create view controller with -init

// Subclass of UIViewControLler

- (void)LoadV1iew

{

MyView *myView = [[MyView alloc] itnitWithFrame: frame];

self.view = myView; // The view controller now owns the view [myView release];

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Creating Your View with Interface Builder

¢ Lay out a view in Interface Builder

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Creating Your View with Interface Builder

¢ Lay out a view in Interface Builder

¢ File’s owner is view controller class

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Creating Your View with Interface Builder

¢ Lay out a view in Interface Builder

¢ File’s owner is view controller class

¢ Hook up view outlet

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Demo:

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View Controller Lifecycle

- C1d)initWithNibName: CNSString *)nibName bundle: CNSBundle *)bundLle

{

if Cself == [Super init ]) {

// Perform initial setup, nothing view-reLlated myData = [[NSMutabLeArray alloc] init];

self.title = @“Foo”;

h

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View Controller Lifecycle

- (vo1id)viewDidLoad

{

// Your view has been Loaded // Customize 1t here tf needed

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View Controller Lifecycle

- Cvoid)viewiLlLAppear: CBOOL)animated

t

[super viewWilLLAppear: animated];

// Your view 1S about to show on the screen LseLf beginLoadingDataFromTheWeb] ;

[self startShow1ngLoadtngProgress |;

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View Controller Lifecycle

- Cvoid)viewiLLDisappear: CBOOL animated

t

[super viewWiLLDisappear: animated];

// Your view 1S about to Leave the screen

[self rememberScroLlLPositton] ;

LseLf saveDataToDisk];

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Loading & Saving Data

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Demo:

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More View Controller Hooks

¢ Automatically rotating your user interface

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Supporting Interface Rotation

- CB0OL )shouLdAutorotateToTnterfaceOr1entat1on:

CUIInterfaceOrientation)interfaceOrientation

i

// This view controller supports all orientations // except for upside-down

return CinterfaceOrientation !=

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Demo:

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Autoresizing Your Views

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Presence

¢ Building an iPhone app for viewing online status updates

= “What are you doing right now?”

¢ Our assignments will be using Twitter API

- Could extend to Facebook updates, IM status, RSS feeds

¢ Four parts, each week builds on the previous one

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Presence - Part 1

° Goals

- Create your own view controller subclasses

= Present a hierarchy using UlNavigationController (next lecture)

allCarrier = 12:17 PM © 0 wilCarrier = 12:17PM

Grading more assignments!

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Demo: