1) The document discusses the behind the scenes workings of a basic "Hello World" iOS application created with a single view application template. It describes how the view controller is linked to the view and view controller class files. 2) It then explains how the app delegate manages the window and links it to the view controller. The view controller acts as the controller in an MVC pattern to manage the view. 3) Additional examples show creating empty window and view controller applications from scratch and linking the interface files to their respective classes. This provides a high-level overview of how the basic components of an iOS app work together.

1. Behind The Scenes
Dr. Thanisa Kruawaisayawan
www.imcinstitute.com

2. Behind The Scene: HelloWorld (Single View Application)
• ViewController is the File’s Owner of ViewController.xib. File’s Owner
represents the object that loaded the nib file from disk and owns this copy of
the nib file.
2

3. Behind The Scene: HelloWorld (Single View Application)
• ViewController has a view linked to View
3

4. Revisit: iOS Application Life Cycle
Souce: http://developer.bada.com/article/A-Comparison-between-iOS-and-bada-Application-Development-Part1 4

5. main() => UIApplicationMain()
• principalClassName
• Pass nil when you have no UIApplication
subclasses
• delegateClassName
• Pass a custom class that implements
UIApplicationDelegate protocol
5

6. AppDelegate.h
• This class implements UIApplicationDelegate Protocol.
• AppDelegate is the delegate of UIApplication object.
• AppDelegate has two properties (named “window”, and “viewController”)
which are instance of UIWindow and ViewController
6

7. AppDelegate.m
• UIWindow has a property named “rootViewController”, which is now pointed
to viewController object.
7

8. Behind The Scene
8

9. Behind The Scene
window
(in AppDelegate) viewController view
=
9

10. Behind The Scene: HelloWorld_Storyboard
• ViewController is the File’s Owner of MainStoryboard.storyboard.
10

11. Behind The Scene: HelloWorld_Storyboard
• ViewController has a view linked to View
11

12. AppDelegate.h
• AppDelegate has two properties (named “window”) which are instance of
UIWindow.
12

13. AppDelegate.m
13

14. HelloWorld_Storyboard-Info.plist
14

15. Behind The Scene
window
(in AppDelegate) viewController view
=
15

16. Model-View-Controller (MVC) Design Pattern
16

17. Model-View-Controller (MVC) Design Pattern
• Model (any data in your program)
Are separated in such a manner
that modifying either the view or
• View (what the user sees) model component of your
program has no effect on one
• Controller (a layer that handles another.
all interaction between the view and model)
17

18. What Files Are In The Project?
• Source Files
• AppDelegate.h & AppDelegate.m
Controller
• ViewController.h & ViewController.m
View
• ViewController.xib / MainStoryboard.storyboard
• Supporting Files
• HelloWorld-Info.plist
• main.m
18

19. New an Empty Application
19

20. HelloWorldEmptyWindow
20

21. AppDelegate.h
• AppDelegate has two properties (named “window”) which are instance of
UIWindow.
21

22. AppDelegate.m
• Window becomes the Key window and is Visible to the screen
22

23. Run and See Result
• This is a window with white background.
23

24. AppDelegate.m
• Add a label into the window
24

25. Run and See Result
25

26. New File > Window > MainWindow.xib
26

27. MainWindow.xib
• Set File’s Owner of MainWindow.xib to Class: UIApplication
27

28. MainWindow.xib
• Drag and drop Object
28

29. MainWindow.xib
• Set Object to Class: AppDelegate
29

30. MainWindow.xib
• Right click at File’s Owner
• Link delegate to App Delegate
30

31. AppDelegate.h
• Add IBOutlet in front of UIWindow
31

32. AppDelegate.m
• Comment codes
32

33. MainWindow.xib
• Right click at App Delegate
• Link window to Window
33

34. MainWindow.xib
• Drag and drop Label and change text into Hello World
34

35. HelloWorldEmptyWindow-Info.plist
• Add Row > Key: Main nib file base name and Value: MainWindow
35

36. Launch the Application
36

37. Run and See Result
37

38. Conclusion for HelloWorldEmptyWindow
• Create a new xib file • Goto AppDelegate.h and put
New File -> Window -> IBOutlet in front of UIWindow
MainWindow.xib *window;
• Click at File's Owner of • Goto Window.xib again and
MainWindow.xib -> change this connect window under Outlets to
class to UIApplication Window
• Drag and drop an Object under
Objects -> select the third tab on • Also in plist file add a row
the right -> change this class to Key: Main nib file base name
AppDelegate
Type: String
• Right click at File’s Owner and Value: MainWindow
connect delegate to App Delegate
38

39. MainWindow.xib
• Drag and drop Round Rect Button and change text into Say Hello
Where to write action code?
39

40. New an Empty Application
40

41. HelloWorldEmptyViewController
41

42. New File > Objective-C class
• Apple calls the library to develop UI in iPhone as Cocoa Touch and in Mac as
Cocoa.
42

43. ViewController
• Enter Class: ViewController, choose Subclass of UIViewController, and
select With XIB for user interface
43

44. ViewController.xib
• File’s Owner of ViewController.xib is Class: ViewController
44

45. ViewController.xib
• Drag and drop label (delete text)
45

46. ViewController.xib
• Drag and drop Round Rect Button (change text to “Say Hello”)
46

47. ViewController.xib to ViewController.h
• Control + Drag from the label in ViewController.xib to ViewController.h
47

48. ViewController.xib to ViewController.h
• Control + Drag from the button in ViewController.xib to ViewController.h
48

49. ViewController.m
• Add code in sayHello method
49

50. AppDelegate.h
• Add codes
50

51. AppDelegate.m
• Add codes
51

52. Run and See Result
52

53. Revisit: New File > Objective-C class > ViewController
• Enter Class: ViewController, choose Subclass of UIViewController, and forget
to select With XIB for user interface
53

54. New File > View > ViewController1.xib
54

55. ViewController1.xib
• Change File’s Owner of ViewController1.xib to Class: ViewController and
Link view of ViewController to View
55

56. ViewController1.xib
• Drag and drop Label and change text to ViewController1
56

57. AppDelegate.m
• Change from ViewController to ViewController1 for initWithNibName
57

58. Run and See Result
58

59. References
• Boonyanit Mathayomchan, Ph.D., “iPhone Application
Development (BASIC)”, 2011
• Chotipat Pornavalai, iPhone Basic #1, Mini Master of iOS
Application #1
• Dave Mark, et.al, “Beginning iOS5 Development: Exploring the iOS
SDK”, 2012
• Joe Conway & Aaron Hillegass, “iPhone Programming: The Big
Nerd Ranch Guide”, 2010
59