This document provides an introduction to Xcode, the integrated development environment (IDE) for building iOS apps. It describes the main parts of Xcode including the navigator panel, inspector panel, libraries and frameworks. It also explains key concepts like the model-view-controller (MVC) pattern, outlets and actions, view controllers and their lifecycles, navigation controllers, table views, and the iOS application lifecycle.

1. Using Xcode

2. Introduction to XCode
• This tutorial will walk you through
Xcode, a software development tool
for Apple’s iOS applications
– We will explore its different parts and
their functions
– This tutorial will teach you how to use
Xcode, but not how to build an app.
• To build an app, you need to know Objective-
C.

3. Useful Terms
• Objective-C: the programming
language used to write iOS
applications, based on C and using
object oriented programming
methods
• Object: a collection of code with its
data and ways to manipulate that
data

4. Useful Terms
• View: how your program presents
information to the user
• Model: how your data is represented
inside of your application

5. App Templates, Pt 2
Tabbed: Like the iPod
app, with lots of
different ways to
view the same
database items
Utility: Like the
weather app, a
main view and a
configuration view
Empty: You
build
everything
from scratch

6. Starting an App
Choose the name you
want for your app
Click ‘Next’
Choose a folder in which
to save your app
Finally, choose your
device
Writing a universal
iOS app is more
difficult than writing
for just one device

7. This is what your screen looks like
now….

8. The main parts we’ll be
focusing on…
1. Navigator Panel
2. Inspector Panel
3. Libraries

9. Navigator Panel

10. The Classes folder
contains two objects:
- The App Delegate
- The View Controller
The extensions:
- .h = header, defines
object
- .m= main/body
-.xib= XML interface
builder

11. The App Delegate
• Handles starting and ending your
app
• Serves as a go-between between iOS
and your app
– Hands off control to your code after
starting

12. The View Controller
• Handles everything that shows up on
screen
• Handles all the info that the onscreen
objects need to display themselves
• Translates between the view and the
model
• Responds to user input and uses that
to change model data
– Responsible for updating view from the
model

13. To help visualize…
From developer.apple.com

14. XML Interface
Builder
This is where you lay
out graphic views
The view controller
knows how to talk to
the objects that have
been created here
Lots of formatting
options

15. Supporting Files, Pt. 1
These are system
files
.plist = property list
Appname-Info.plist =
contains info about
your app for the iOS.
It is an XML file that
includes the options
you put on your app
(which device, etc.)
InfoPlist.strings =
helps to
internationalize your
app
- Language

16. Supporting Files, Pt. 2
Main.m = low level.
Starts app and gives
to the App Delegate.
Never change this
file.
.pch = pre-compiled
header
Appname-Prefix.pch
= generated by the
system to speed up
builds

17. Frameworks
Frameworks contains a lot of
already written code provided
by the system
- A library of code bits
- Related to the Libraries
menu on the right of
Xcode
UIKit = contains code for
everything that interfaces
with the user (views)
Foundation = alll the
components used to build the
model
CoreGraphics = handles
drawing on the screen

18. Inspector Panel
• This area contains
utilities panels that
let you change
properties of your
app’s view objects,
like:
• Colors
• Sizes
• Images
• Button actions

19. Libraries
• Different goodies
depending on which
icon you click
– From left to right:
• File templates
• Code snippets
• View Objects
• Media/Images

20. Model, View, Controller
(MVC)
iOS applications follows
the MVC design pattern.
• Model: Represents the business
logic of your application
• View: Represents what the user sees
in the device

21. • Controller: Acts as a mediator
between the Model and View. There
should not be any direct
conversation between the View and
the Model. The Controller updates
the View based on any changes in
the underlying Model. If the user
enters or updates any information in
the View, the changes are reflected
in the Model with the help of the
Controller.

22. How does a View or Model interact
with the Controller?
• Views can interact with the Controller with
the help of targets or delegates.
• Whenever the user interacts with a View,
for example by touching a button, the
View can set the Controller associated with
it as the target of the user’s action. Thus
the Controller can decide on further
actions to be taken. We will see how this
can be achieved in the later part of this
tutorial.
• Views can also delegate some of the
actions to the Controller by setting the
Controller as its delegate.

23. MVC

24. • The Model notifies the Controller of
any data changes, and in turn, the
Controller updates the data in the
Views. The View can then notify the
Controller of actions the user
performed and the Controller will
either update the Model if necessary
or retrieve any requested data.

25. Outlet And Actions Outlet:
• ViewController talks to View by using
Outlet. Any object (UILabel, UIButton,
UIImage, UIView etc) in View can have an
Outlet connection to ViewController. Outlet
is used as @property in ViewController
which means that:
• you can set something (like Update
UILabel's text, Set background image of a
UIView etc.) of an object by using outlet.
• you can get something from an object
(like current value of UIStepper, current
font size of a NSAttributedString etc.)

26. Action:
• View pass on messages about view to
ViewController by using Action (Or in
technical terms ViewController set itself
as Target for any Action in View). Action is
a Method in ViewController (unlike Outlet
which is @property in ViewController).
• Whenever something (any Event)
happens to an object (like UIbutton is
tapped) then Action pass on message to
ViewController. Action (or Action method)
can do something after receiving the
message.
Note: Action can be set only by UIControl's
child object; means you can't set Action
for UILabel, UIView etc.

27. Application Life
Cycle

29. • application:willFinishLaunchingWithOp
tions:
—This method is your app’s first
chance to execute code at launch
time.
• application:didFinishLaunchingWithOp
tions:
—This method allows you to perform
any final initialization before your
app is displayed to the user.
• applicationDidBecomeActive:—Lets
your app know that it is about to
become the foreground app. Use this
method for any last minute
preparation.

30. • applicationWillResignActive:—Lets you know
that your app is transitioning away from
being the foreground app. Use this method to
put your app into a quiescent state.
• applicationDidEnterBackground:—Lets you
know that your app is now running in the
background and may be suspended at any
time.
• applicationWillEnterForeground:—Lets you
know that your app is moving out of the
background and back into the foreground,
but that it is not yet active.
• applicationWillTerminate:—Lets you know
that your app is being terminated. This
method is not called if your app is
suspended.

31. Application State
• Not running
• Inactive
• Active
• Background
• Suspended

33. View controller
• Connect the view and the controller
with
IBOutlet

34. View Controller Life Cycle
• - (void)viewDidLoad;
• -( B(OvoOidL))vaineiwmWatiellAd;ppear:
• -( B(OvoOidL))vaineiwmDaitdeAdp; pear:
• - (void)viewWillDisappear:
(BOOL)animated;
• - (void)viewDidDisappear:
(BOOL)animated:

36. UINavigationController
• The UINavigationController class
implements a specialized view
controller that manages the
navigation of hierarchical content.
This navigation interface makes it
possible to present your data
efficiently and makes it easier for the
user to navigate that content.
• A navigation controller object
manages the currently displayed
screens using the navigation stack

37. TableView Control
• Table View is one of the common UI
elements in iOS apps
• Most apps, in some ways, make use of
Table View to display list of data
• The “UITableViewDelegate” and
“UITableViewDataSource” are known as
protocol in Objective-C. Basically, in order
to display data in Table View, we have to
conform to the requirements defined in the
protocols and implement all the
mandatory methods.

38. UITableViewDelegate
• UITableViewDelegate, deals with the
appearance of the UITableView.
Optional methods of the protocols let
you manage the height of a table
row, configure section headings and
footers, re-order table cells, etc.

39. UITableViewDataSource
• We’ll use the table view to present a
list of recipes. So how do you tell
UITableView the list of data to
display? UITableViewDataSource is
the answer. It’s the link between your
data and the table view. The
UITableViewDataSource protocol
declares two required methods
• tableView:cellForRowAtIndexPath
• tableView:numberOfRowsInSection