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iOS - iPhone/iPad

Application DevelopmentWorkshop

Part 1

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What do you need?

•Previous experience in another Object Oriented Programming (OOP) language will be helpful

•Some understanding of C can be helpful, but is not required. Objective-C builds on C++.

•Development Environment (IDE) is helpful•Mac computer running OS X Lion or higher!• If you plan to submit to the App Store, you will

need Apple devices to do real testing on. The simulator is not good enough.

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Introduction

• iOS is the operating system that runs iPhones, iPod Touches, iPads, and Apple TVs.

•The language used to develop software for iOS is Objective-C. (very similar to C)

•This workshop will teach you how to get started but will not have time to teach you everything.

•This workshop is good preparation for a real full iPhone/iPad, iOS Development class!

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What is iOS?

• iOS is an OS. It’s a subset of Mac OS X.•The iOS SDK is the software development kit that

allows application programs to utilize classes and frameworks provided by the SDK. This workshop will focus on iOS SDK 5

• iOS is multitasking and runs on different devices (iPhones, iPod Touches, iPads, and Apple TVs).

•Apple provides an IDE called Xcode.•Xcode is the IDE used by iOS (and OS X)

developers. It does NOT run on MS Windows.•Xcode provides an interface to the compiler, editor,

debugger, and code profiling tools.

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Device Features

•SQLite for structured data storage•Media support for common audio, video, and still

image formats (MPEG4, H.264, MP3, AAC, AMR, JPG, PNG, GIF)

•GSM Telephony (hardware dependent)•Bluetooth, EDGE, 3G, and WiFi (hardware

dependent)•Camera, GPS, compass, and accelerometer

(hardware dependent)•Rich development environment including a device

simulator, tools for debugging, memory and performance profiling

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Download the iOS SDK

•Download the latest from the Apple App store•This is only available for Apple Macintosh

computers• It’s free•To build to device and submit to the app store,

you will be required to becomes a register Apple iOS developer

• It’s $99 year for the basic account• If you plan to get a job in iOS development, you

will need to establish a basic account and submit something to the Apple Store. Maybe a game?

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Let’s get started - Launch Xcode

• You are presented with the Welcome screen:•Create a new project•Connect to a repository•Learn about using

Xcode•Go to Apple’s Portal

•Go ahead and click on “Create a new project”

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Project Template

•There are several predefined templates to help you get started on a new project

•For now, click on Single View Application

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Project Options

• The Product Name is the name of your app

• Company Identifier is your organization name – such as edu.itu (reverse domain)

• Class Prefix (leave empty)• Device Family: iPad, iPhone,

Universal (Universal means that a single binary will have screens for iPhone, iPod Touch, and iPads)

• Storyboards• Automatic Reference Counting• Include Unit Tests (leave

unchecked as we are not using)

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Source Control

• Asks for a location for Source Control

• By Default, it will use a local GIT repository

• New developers not used to source control – this is extremely useful!

• It keeps track of versions, lets you see what’s changed, and will undoubtedly be used in any team project you run into in the “real” world

• GIT and Subversion are two popular source controls systems – there are many others to choose from

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Where do I start?

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Let’s build the default project

•Click the Run button (upper left of the screen)•The iPad simulator will launch (You can also

change this to iPhone if you want)•You will have a blank white screen•Press Command-Q to end the simulator

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Quick Terminology: MVC

•Model-View-Controller (MVC)•MVC is the paradigm of iOS programming•Model: Holds data, should know nothing of the

interface•View: Code for getting data in/out of a view.

Deals with items like buttons, lists, tables, etc•Controller: Keeps the Model objects and View

objects in sync

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Quick Terminology: Delegate

•AppDelegate.h•AppDelegate.m

•The Delegate is essentially the “controller” of your app. It links buttons, labels and views together

•.h files are header files and interfaces are defined here

•.m files are implementation files. These contain your classes, code, etc.

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Quick Terminology: Storyboard

•These are new to iOS5•Storyboards help you graphically lay out your app

before you code it.• It makes it easy to see the “flow” of your app•You are advised to use Storyboards going forward

with you iOS programming adventures• If you have tinkered with iOS in the past, you might

be asking about the xib/nibs. They are still there, however, Storyboards offer similar functionality and make it easier to visualize your views.

•We will not be covering nibs in this workshop.

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Quick Terminology: ARC

•Automatic Reference Counting (ARC)•The LLVM 3.0 compiler handles memory

management for you• It is not a garbage collector!•Prior to iOS5 – memory management was the single

most difficult item to grasp in Objective-C. •Unless you have specific reasons, all of your projects

should use ARC.

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Quick Terminology: Unit Tests

•We will not be discussing Unit Tests in this workshop

•Be advised – unit tests are very useful for your programs

•The tests can help you make sure your code changes are not breaking anything.

•The goal is to be able to find bugs quicker and fix them before your code goes to QA (or the customer!)

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Click on the iPhone Storyboard

•It shows a blank view

•It looks like you are on a sheet of graph paper

•There are two buttons – below•First Responder•View Controller

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Find the Label

•In Xcode, lower right hand corner, scroll until you find the object Label

•Drag Label to the blank view

•Double click on the Label you added, and change it to say “Hello World”

•Do the same steps for the iPad Storyboard

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Run the project

•The iPad and iPhone projects should now display Hello World!

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Next, add two buttons to your view

•Find the Round Rect Button, drag two to the view

•Double-click on one of the buttons and type Hello

•Double-click on one of the buttons and type Goodbye

•Run your project, click on the buttons

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Nothing Happens – we have to tell it to do something

•Click on the Assistant Editor

•It looks like a tuxedo•It will be in the upper right hand corner of your screen

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Linking the ViewObject to your ViewController…

•You will see your ViewObject in the middle of the screen

•The right hand side of the screen should be the ViewController.h file

View Object

ViewController.h

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Link the label…

• Single click on your Hello World label

• While holding down the Control key, left click-drag to the ViewController.h file

• You need to drag between the @interface and @end in the code

• This will make a new property• For the name, call it helloLabel

so we can easily recognize what it is

• This step will allow us to make changes to the UILabel

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@interface and @end

•Remember that Objective-C is an extensive to the C language

•The @ symbol denotes an Objective-C keyword

•@interface is the start of a class.•@interface Classname: Superclass•Anything between the declaration and end is part of the class

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@property (weak, nonatomic) IBOutlet UILabel *helloLabel;

•A property is an attribute of the class•Getters and Setters are automatically created for

you•Weak is a memory management term•Nonatomic has to do with adding mutexes around

your getters and setters• IBOutlet stands for Interface Builder Outlet.• Interface Builder still exists in iOS5 but we are

using the new Storyboard feature instead.

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@synthesize helloLabel

•Synthesize – this creates the accessor/mutators (getters/setters) for you

•You can write your own if you want, but in general, there is no reason to do this.

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Link the rest of the buttons

•Link helloButton to ViewController.h

•Link goodbyeButton to ViewController.h

•When done, you will have two properties

•Now, switch the Assistant window to the ViewController.m file

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TouchUpInside Actions

TouchUpInside events occur if you touch a button and lift off while inside the buttonThis corresponds to a user tapping a buttonRight-Click on the Hello buttonOn the far right, locate Touch Up InsideLeft click-drag this over to your ViewController.mNotice it creates some codeDo the same for the goodbye button

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IBAction

•You created two IBActions•Actions signify something that happens when you do something for example, push a button.

•When you push a button, it fires the action•These are currently empty methods

- (IBAction)helloPushed:(id)sender {}

- (IBAction)goodbyePushed:(id)sender {}

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Change the UILabel

- (IBAction)helloPushed:(id)sender { self.helloLabel.text=@"Hello Pushed";}- (IBAction)goodbyePushed:(id)sender { self.helloLabel.text=@"Goodbye Pushed";}

• Self refers to the ViewController class• We defined the property helloLabel earlier• Text is a property of UILabel’s that we can set.• The @”Some text” is an NSString object that UILabels can

display.• Run your program and push the buttons. You should see

the UILabel change when you press the buttons

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Tab Controller

• If you’ve ever used an iOS device, you have come across apps that use the tab controller.

•Several of the built in apps (such as the phone app) use this controller

•For the next exercise, we are going to create a simple tab controller

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Create a new project

•Close any existing projects you have open (to make things easier!)

•Select File->New->Project from the application menu

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Select Tab Template

•Select the “Tabbed Application” Template for your project

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Set Options

•For product name, call it tabDemo

•Whatever you used for Company Identifier should be set – if not, edu.itu is ok

•Leave Class Prefix blank•For Device family, choose

iPhone (to keep it simple)•Enable Storyboards and

Arc•Do not select Unit Tests

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Look at the Storyboard

• Click on MainStoryboard.Storyboard

• Notice how the Tab Bar Controller is shown

• It also shows the child views associated with the tab bar buttons

• This lets the developer see the views and path to them at a quick glance.

• Go ahead and run the project, observe what happens when you tap the tab items. It switches between the views

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Let’s add a new class: ThirdViewController

•On the left hand side, right-click on the tabDemo folder and select New File

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Pick the type of file

•We are adding a new ViewController – so select Objective-C class

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Pick the options

• For Class, type in Third• In the Sublass combo box,

select UIViewController• The IDE will change your

class name• It is good naming convention

to have the class be description – so in this case, ThirdViewController lets any developer know this is a ViewController

• Leave Targeted for iPad and XIB unchecked

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Create

•Take the default options, click the Create button

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We now have a .h and .m

•Notice that you now have two files

•ThirdViewController.h and ThirdViewController.m

•If you look at the files, they are basically “skeleton” classes ready for the developer

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Add another View Controller

•Add a new View Controller to the Storyboard

•After you add it, it will not be linked to any view

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Our new view, all alone

•Notice that Storyboard does not have any arrows pointing to it

•The developer will have to make the association as this view could be a sub view of any of the views shown

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Link this ViewController to the Tab Controller

•Hold down the Control key, left-click drag from the Tab Controller to the new view we just added

•This tells Storyboard that this view is going to be accessed from the tab controller

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Select Relationship

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Label this before we forget

•Click on the Text•Change this to say Third

•We do not have any graphics – if we did, we would want to go ahead and add a graphic for this.

•Note: you will need graphics for standard iPhones, retina, and iPads.

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Lets be more specific about the class

• Left Click on your new view in Storyboard – icon on right bottom

• Click the Identify Inspector (upper right)

• Notice how the class is currently UIViewController

• We need to make this to be associated with our ThirdViewController (which is a subclass of UIViewController)

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Select ThirdViewController

•From the combo box, scroll until you find ThirdViewController

•This will let us do any custom actions we might need to do

•Remember: ThirdViewController has all of the methods and properties of a UIViewController!

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Let’s Replace the First View

• We are going to replace the FirstViewController with a TableViewController

• Click on First View, hit the Delete button to remove it

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Drag a Table View Controller

• From the Object Library, drag over a Table View Controller

• A good spot would be where you just deleted the other view controller

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Embed Navigation Controller

•From the Xcode menu bar, select Editor->Embed In->Navigation Controller

•Notice that another view controller is added to the Storyboard canvas

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Check it out

• This is what we did in the previous slide

• Since the Navigation Controller is a container, there is a relationship between the Navigation controller and the table view controller. (Noted by the connecting arrow)

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Hook up the Scenes

•Ctrl-drag from the Tab Bar controller to the Navigation controller

•Select Relationship – View Controllers

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Look at Storyboard now

• The relationship is defined

• When we added this, it added an entry labeled “Item” as the last tab bar button

•Drag this “Item” and make it the first entry in our tab bar

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Fix up the tab bar items

•Drag item to the left most position

•Also, let’s rename this back to First

•Double-click on Item in the Navigation Controller scene, change text to First

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Name the Navigation bar

•In the Table View window, double-click on the Title bar.

•Type in “Things” to give the Navigation bar a name.

•In a “real” app, you would type something descriptive and meaningful to the user.

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The Navigation Bar has a title

•You can now see the title has a name.

•If you have noticed, we have been getting a warning from the compiler for our storyboard.

•“Prototype table cells must have reuse identifiers”

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Let’s get rid of the warning

• Warnings are typically not something you want in your program.

• We are getting this warning because we have not configured the cells yet – so the compiler does not know what they are.

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Table View Controller

• Click on the blank prototype cell

• Next, click on the attributes inspector and set Style to Subtitle.

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Attributes Inspector

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More cell attributes

•Set the Accessory attribute to Disclosure Indicator.

•Give the cell an identifier of ThingsCell.

•The warning from Xcode is a reminder to developers – there is something you need to do if you want this to work.

•(Side note – warnings are something you should not overlook. Several program crashes can stem from warnings people don’t pay attention to.)

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Add a UIViewController subclass template…

• Add a new file to the project.• Choose UIViewController subclass template.

• Name the class ThingsViewController, this will be a subclass of UITableViewController

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New file

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Objective-C Class

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ThingsViewController

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Create to add to project

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Set the class with Identify Inspector

• Click on the TableViewController object (the whole object will be outlined in blue)

• Now, click class and select ThingsViewController

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Build and run!

• Go ahead and build the app• You can now add items to the table view if you want to continue working with this app.

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HelloTabBar Example

•Download:•http://bhecker.com/ip-HelloTabBar.zip•Save to your desktop.•Double-click to uncompress the file•Double-click on “HelloTabBar.xcode.proj” to load the project in XCode

•Examine and customize as you wish!

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The End of Part 1

Next… Part 2Objective-C Programming