iOS - iPhone/iPad Application Development Workshop Part 1

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.

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!

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.

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

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?

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”

Project Template There are several predefined templates to help you get started on a new project For now, click on Single View Application

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)

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

Where do I start?

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

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

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.

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.

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.

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!)

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

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

Run the project The iPad and iPhone projects should now display Hello World!

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

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

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

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

@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

@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.

@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.

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

TouchUpInside Actions TouchUpInside events occur if you touch a button and lift off while inside the button This corresponds to a user tapping a button Right-Click on the Hello button On the far right, locate Touch Up Inside Left click-drag this over to your ViewController.m Notice it creates some code Do the same for the goodbye button

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 {

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

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

Create a new project Close any existing projects you have open (to make things easier!) Select File->New->Project from the application menu

Select Tab Template Select the “Tabbed Application” Template for your project

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

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

Let’s add a new class: ThirdViewController On the left hand side, right-click on the tabDemo folder and select New File

Pick the type of file We are adding a new ViewController – so select Objective-C class

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

Create Take the default options, click the Create button

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

Add another View Controller Add a new View Controller to the Storyboard After you add it, it will not be linked to any view

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

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

Select Relationship

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.

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)

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!

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

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

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

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)

Hook up the Scenes Ctrl-drag from the Tab Bar controller to the Navigation controller Select Relationship – View Controllers

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

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

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.

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”

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.

Table View Controller Click on the blank prototype cell Next, click on the attributes inspector and set Style to Subtitle.

Attributes Inspector

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.)

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

New file

Objective-C Class

ThingsViewController

Create to add to project

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

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.

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!

The End of Part 1 Next… Part 2 Objective-C Programming