The document provides an overview of programming with the iPhone SDK, describing the iPhone's features and limitations, the components of the SDK including Xcode, Interface Builder and frameworks, and how to develop applications using Objective-C including defining classes, methods, properties and protocols. It also includes examples of creating a simple Fraction class to demonstrate Objective-C concepts.

1. Programming with iPhone SDK
Javier González Sánchez
Maria Elena Chávez Echeagaray
Copyright is held by the author/owner(s).
OOPSLA 2009, October 25–29, 2009, Orlando, Florida, USA.

2. Expectatives

3. Introduction
1.

4. What is iPhone ?
Limited screen size. You have a 480 x 320
pixels screen.
Light mobile. Height: 4.5 inches, Width: 2.4
inches, Depth 0.48 inches, Weight: 4.8
ounces.
One application at a time. It only can
handle one application running at a time.
Only one window. iPhone applications only
can have one window at a time.
Five seconds limit. When the user hits the
home button, your application will have 5
seconds to save data, close and give up its
control. If it takes more than that, it will be
terminated.
4

5. What is iPhone ?
CPU. 412 | 600 MHz
Memory administration. It has 128 | 256
MB of physical RAM and 8 | 32 GB of
storage.
File Management. It provides each
application with a sandbox (2GB), where the
application can read/write files, store
documents, preferences and data.
Different physical interface. iPhone do not
have a physical keyboard and a mouse.
Instead of that we have multitouch.
Other features. iPhone includes Core
Location, 3 megapixels built-in camera and
photo library, a built-in accelerometer,
proximity sensor, and ambient light sensor.
And a Phone with WiFi
Memory management without a “garbage
collector”. 5

6. iPhone SDK
2.

7. Developer Connection
7

8. How does this works?
 There is a free SDK that allow you to create your applications, and test them
in a Simulator.
 Ok!, so what?, Is this a business?
 There is a Standard or the Enterprise version of the SDK. They cost $99 and
$299 respectively.
 Now you can upload your application to your iPhone or distribute them in
Apples’ iPhone App Store.
 They take care of the process, you then take care or your development.
8

9. Installation

10. iPhone SDK
• Sample code
Documentation • Reference libraries
• Coding how-to
• UIKit
• Foundation
Frameworks • OpenGL / Quartz / Core Graphics
• Media
• Xcode,
Tools • Interface Builder
• iPhone Simulator
10

11. Frameworks
 Foundation
Cocoa Touch
 UIKit
 OpenGL ES, Quartz,
Media
 OpenAL, Core Audio,
 Core Animation
 Core Location,
Core Services
 CFNetwork,
 SQLite,
 Security,
 UNIX sockets
Core OS
 File system
 Memory allocation 11

12. Tools
We are going to be working with:
 Xcode. Apple's Integrated Development Environment (IDE).
 Interface Builder (IB). environment to facilitate the development of your GUI's
and to give functionality to its components.
 iPhone Simulator. It allows you to run your iPhone programs on your Mac.
NOTE: the free SDK does not allow you to upload your applications to your
iPhone (or iPod Touch) or distribute your software in Apples' iPhone App Store. In
order to do this, you have to get the Standard ($99) or the Enterprise ($299)
version of the SDK.
 Instruments. environment It lets you analyze the performance of your iPhone
applications while running in the simulator or on a device.
12

13. Xcode
13

14. Interface Builder
Library
View
.xib file
View
Instance of UIView, this is
the area the users interact Design area
GUI elements with 14

15. Interface Builder
 Interface Builder is the tool you use to assemble your application’s user interface
visually.
 You assemble your application’s window by dragging and dropping preconfigured
components onto it.
 The components include standard system controls such as switches, text fields, and buttons,
and also custom views to represent the views your application provides.
 After you’ve placed the components on the window’s surface, you can establish the
relationships between those objects and your code. When your interface looks the way you
want it, you save the contents to a nib file, which is a custom resource file format.
 The nib files you create in Interface Builder contain all the information that the UI Kit
needs to recreate the same objects in your application at runtime. Loading a nib file
creates runtime versions of all the objects stored in the file, configuring them exactly
as they were in Interface Builder.
15

16. Demo
 Hello World

17. Model(delegate) + Controller + View
View
Include
XIB files
Model Controller
Delegates
17

18. Objective-C
3.

19. Objective-C
 Is a simple computer language designed to enable sophisticated OO programming.
 Extends the standard ANSI C language by providing syntax for defining classes,
methods, and properties, as well as other constructs that promote dynamic
extension of classes.
 Based mostly on Smalltalk (class syntax and design), one of the first object-oriented
programming languages.
 Includes the traditional object-oriented concepts, such as encapsulation,
inheritance, and polymorphism.
19

20. Files
Extension Source Type
.h Header files. Header files contain class, type, function, and
constant declarations.
.m Source files. This is the typical extension used for source
files and can contain both Objective-C and C code.
.mm Source files. A source file with this extension can contain C+
+ code in addition to Objective-C and C code.
This extension should be used only if you actually refer to C+
+ classes or features from your Objective-C code.
20

21. #import
 To include header files in your source code, you can use the standard #include, but….
 Objective-C provides a better way #import. it makes sure that the same file is never
included more than once.
#import
“MyAppDelegate.h”
#import
“MyViewController.h”
#import
<UIKit/UIKit.h>
21

22. Class
 The specification of a class in Objective-C requires two distinct pieces: the
interface (.h files) and the implementation (.m files).
 The interface portion contains the class declaration and defines the instance
variables and methods associated with the class.
@interface
…
@end
 The implementation portion contains the actual code for the methods of the
class.
@implementation
…
@end
22

23. Class
Class name
@interface
MyClass
:
NSObject
Parent class
{
int
count;
id
data;
Instance variables
NSString*
name;
}
-­‐
(id)initWithString:(NSString
*)aName;
methods
+
(MyClass
*)createMyClassWithString:
(NSString
*)
aName;
@end
23

24. Class
Class name
@implementation
MyClass
-­‐
(id)initWithString:(NSString
*)
aName
{
if
(self
=
[super
init])
{
count
=
0;
data
=
nil;
methods
name
=
[aName
copy];
return
self;
}
}
+
(MyClass
*)createMyClassWithString:
(NSString
*)
aName
{
return
[[[self
alloc]
initWithString:aName]
autorelease];
}
@end
24

25. Methods
 A class in Objective-C can declare two types of methods:
 Instance method is a method whose execution is scoped to a particular instance of the
class. In other words, before you call an instance method, you must first create an
instance of the class.
 Class methods, by comparison, do not require you to create an instance.
Method type identifier One or more signature keywords
-­‐(void)insertObject:(id)anObject
atIndex:(NSUInteger)index;
Return type Parameters with (type) and name
25

26. Methods
So
the
declaration
of
the
method
insertObject
would
be:
-­‐(void)insertObject:(id)anObject
atIndex:(NSUInteger)index
Method type identifier, is (-) to instance methods, (+) to class methods.
And
the
line
to
call
the
method
would
be:
[myArray
insertObject:anObj
atIndex:0];
26

27. Properties
 They are simply a shorthand for defining methods (getters and setters) that
access existing instance variables.
 Properties do not create new instance variables in your class declaration.
 Reduce the amount of redundant code you have to write. Because most
accessor methods are implemented in similar ways
 You specify the behavior you want using the property declaration and then
synthesize actual getter and setter methods based on that declaration at
compile time.
27

28. Properties
In the interface we have:
{
BOOL
flag;
NSString*
myObject;
UIView*
rootView;
}
@property
BOOL
flag;
@property
(copy)
NSString*
myObject;
//
Copy
the
object
during
assignement
@property
(readonly)
UIView*
rootView;
//
Create
only
a
getter
method.
…
And in the implementation side we have:
@syntetize
flag;
@syntetize
myObject;
@syntetize
rootView;
…
myObject.flag
=
YES;
CGRect
viewFrame
=
myObject.rootView.frame;
28

29. Properties
Writability
 Readwrite. You can read/write it. This is the default value.
 Readonly. You can only read it.
Setter semantics (mutually exclusive)
 Assign. Specifies that the setter uses simple assignment. This is the default value.
 Retain. Specifies that a pointer should be retained.
 Copy. Specifies that a copy of the object should be used for assignment.
Atomicity (multithreading)
 Nonatomic. Specifies that accessor methods are not atomic.
 The default value is atomic but there is no need to specify it.
29

30. Protocols and Delegates
 Protocols are not classes themselves. They simply define an interface that other objects
are responsible for implementing
 A protocol declares methods that can be implemented by any class.
 In iPhone OS, protocols are used frequently to implement delegate objects. A delegate
object is an object that acts on behalf of, or in coordination with, another object.
 The declaration of a protocol looks similar to that of a class interface, with the exceptions
that protocols do not have a parent class and they do not define instance variables.
 In the case of many delegate protocols, adopting a protocol is simply a matter of
implementing the methods defined by that protocol. There are some protocols that
require you to state explicitly that you support the protocol, and protocols can specify
both required and optional methods.
30

31. Example: Fraction
Fraction.h
Fraction.m
#import
<Foundation/NSObject.h>
#import
"Fraction.h"
#import
<stdio.h>
@interface
Fraction:
NSObject
{
int
numerator;
@implementation
Fraction
int
denominator;
}
@synthesize
numerator;
//Properties
instead
of
getters
and
@synthesize
denominator;
//setters
@property
(nonatomic)
int
numerator;
//
Output
Print
@property
(nonatomic)
int
denominator;
-­‐(void)
print
{
printf("%i/%i",
numerator,denominator);
}
//Output
print
@end
-­‐(void)
print;
@end
31

32. Example: Fraction
main.m
#import <stdio.h>
#import "Fraction.h"
int main( int argc, const char *argv[] ) {
Fraction *frac = [[Fraction alloc] init];
frac.numerator = 1;
frac.denominator=3;
printf( "The fraction is: " );
[frac print];
printf( "n" );
[frac release]
return 0;
}
32

33. Strings
 The NSString class provides an object wrapper.
 Supports storing arbitrary-length strings, support for Unicode, printf-style
formatting utilities, and more.
 Shorthand notation for creating NSString objects from constant values.
Precede a normal, double-quoted string with the @ symbol.
NSString*
myString
=
@”Hello
Worldn";
NSString*
anotherString
=
[NSString
stringWithFormat:@"%d
%s",
1,
@"String”];
33

34. Exercise
 Fraction

35. Let us Code:
Outlet and Actions
4.

36. What about main method ?
int main(int argc, char *argv[]) {
NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
int retVal = UIApplicationMain(argc, argv, nil, nil);
[pool release];
return retVal;
}
36

37. Model(delegate)
View
Include
XIB files
Protocol
implementation
Model Controller
Delegates
UIApplicationDelegate
UIAccelerometerDelegate
UILocationManagerDelegate
37

38. UIApplicationDelegate
#import <UIKit/UIKit.h>
@class TutorialEvaluationViewController;
@interface TutorialEvaluationAppDelegate : NSObject <UIApplicationDelegate> {
UIWindow *window;
TutorialEvaluationViewController *viewController;
}
@property (nonatomic, retain) IBOutlet UIWindow *window;
@property (nonatomic, retain) IBOutlet TutorialEvaluationViewController *viewController;
@end
38

39. UIApplicationDelegate
#import "TutorialEvaluationAppDelegate.h”
#import "TutorialEvaluationViewController.h”
@implementation TutorialEvaluationAppDelegate
@synthesize window;
@synthesize viewController;
- (void)applicationDidFinishLaunching:(UIApplication *) application {
// Override point for customization after app launch
[window addSubview:viewController.view];
[window makeKeyAndVisible];
}
- (void) dealloc {
[viewController release];
[window release];
[super dealloc];
}
@end
39

40. View (go back to IB)
View
Include
XIB files
IBOutlet
IBAction
Protocol
implementation
Model Controller
Delegates
UIApplicationDelegate
UIAccelerometerDelegate
UILocationManagerDelegate
40

41. Controller
View
Include
XIB files
IBOutlet
IBAction
Protocol
implementation
Model Controller
Delegates
UIApplicationDelegate
UIAccelerometerDelegate
UILocationManagerDelegate
41

42. Actions and Outlets
 Outlet: is a pointer that points an
object in the NIB file.
• Action: objects in the nib can trigger
special methods in our controller. These
special methods are known as action
methods.
42

43. FooViewController.h
#import <UIKit/UIKit.h>
@interface FooViewController : UIViewController {
IBOutlet UILabel *label;
}
@property (retain, nonatomic) UILabel *label;
- (IBAction)buttonPressed:(id)sender;
@end
43

44. FooViewController.m
#import ”FooViewController.h"
@implementation FooViewController
@synthesize label;
-(IBAction)buttonPressed:(did)sender{
label.text = [sender titleForState:UIControlStateNormal];
}
- (void)dealloc {
[label release]
[super dealloc];
}
@end
44

45. Connecting
 We need to connect the elements in the interface with its functionality, i.e., we have
to connect our View with the File's Owner.
 With this connection we are telling our controller that when our application starts it
loads the TutorialEvaluationViewController.xib file into memory and get control of it.
UI
45

46. Exercise

47. Solution
IBOutlet UILabel *label;
IBOutlet
UIImageView
*logo;
@property
(nonatomic,
retain)
UILabel
*label;
@property
(nonatomic,
retain)
UIImageView
*logo;
@synthesize
label;
@synthesize
logo;
-­‐(IBAction)pressButtonFlorida:(id)sender{
label.text
=
@"Welcome
to
Florida";
logo.image
=
[UIImage
imageNamed:@"MickeyMouse.gif"];
}
-­‐(IBAction)pressButtonArizona:(id)sender{
label.text
=
@"Greetings
from
Arizona";logo.image
=
[UIImage
imageNamed:@"ASU_logo.png"];
}

48. Let us Code:
Touch Events
5

49. Handling Touch Events
All UIViewController inherit from UIResponder, and is able to handle touch Event.
In order to do this we use these three methods.
-­‐
(void)touchesBegan:(NSSet
*)touches
withEvent:(UIEvent
*)event;
-­‐
(void)touchesMoved:(NSSet
*)touches
withEvent:(UIEvent
*)event;
-­‐
(void)touchesEnded:(NSSet
*)touches
withEvent:(UIEvent
*)event;
49

50. Exercise

51. Solution
-­‐(void)touchesBegan:(NSSet
*)touches
withEvent:(UIEvent
*)event{
touchLabel.text
=
@"began";
NSUInteger
numTaps
=
[[touches
anyObject]
tapCount];
if
(numTaps
==
1)
[self.view
setBackgroundColor:
[UIColor
redColor]];
else
if
(numTaps
==
2)
[self.view
setBackgroundColor:
[UIColor
blueColor]];
else
if
(numTaps
==
3)
[self.view
setBackgroundColor:
[UIColor
yellowColor]];
}
-­‐(void)touchesMoved:(NSSet
*)touches
withEvent:(UIEvent
*)event{
CGPoint
point
=
[[touches
anyObject]
locationInView:self.view];
NSString
*touchesMessage
=
[[NSString
alloc]
initWithFormat:@"%f,
%f",
point.x,
point.y];
touchLabel.text
=
touchesMessage;
[touchesMessage
release];
}
-­‐(void)touchesEnded:(NSSet
*)touches
withEvent:(UIEvent
*)event{
touchLabel.text
=
@"ended";
}

52. Demo
 Fireworks

53. Let us code:
Autorotate and Accelerometer
6

54. AutoRotate
The UIViewController class provides the infrastructure needed to rotate your interface and
adjust the position of views automatically in response to orientation changes.
-(BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation interfaceOrientation {
return YES;
//return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
interfaceOrientation values:
 UIInterfaceOrientationPortrait
 UIInterfaceOrientationPortraitUpsideDown
 UIInterfaceOrientationLandscapeLeft
 UIInterfaceOrientationLandscapeRight
54

55. AutoRotate adjustments
55

56. Accelerometer
Measure of Gravity acceleration:
0g
1g
2.3g
56

57. Reading the Accelerometer
 UIAccelerometer object in UIKit allow you to access to the raw accelerometer
data directly. This object reports the current accelerometer values.
 To get an instance of this class, call the sharedAccelerometer method of
UIAccelerometer class.
 The updateInterval property define the reporting interval in seconds.
-­‐(void)viewDidLoad
{
UIAccelerometer
*accelerometer
=
[UIAccelerometer
sharedAccelerometer];
accelerometer.delegate
=
self;
accelerometer.updateInterval
=
1.0/60;
[super
viewDidLoad];
}
57

58. Reading the Accelerometer
 A delegate (UIAccelerometerDelegate) will receive acceleration events.
@interface
FooViewController:
UIViewController
<UIAccelerometerDelegate>
 Use accelerometer:didAccelerate: method to process accelerometer data.
-­‐(void)accelerometer:(UIAccelerometer
*)accelerometer
didAccelerate:
(UIAcceleration
*)acceleration
{
NSString
*s
=
[[NSString
alloc]
initWithFormat:@"%f,
%f,
%f",
acceleration.x,
acceleration.y,
acceleration.z];
accLabel.text
=
s;
[s
release];
}
58

59. Exercise

60. Demo
 Rolling ball

61. Core Location
7

62. Core Location
The Core Location framework monitors signals coming from cell phone towers
and Wi-Fi hotspots and uses them to triangulate the user's current position.
62

63. Getting the User's Current Location
 Create an instance of CLLocationManager class.
It
is
necessary
to
include
the
CoreLocation.framework
#import
<CoreLocation/CoreLocation.h>
@interface
FooViewController:
UIViewController<CLLocationManagerDelegate>
 To begin receiving notifications, assign a delegate and call the
startUpdatingLocation method.
-­‐(void)viewDidLoad
{
CLLocationManager
*locationManager=
[[CLLocationManager
alloc]
init];
[locationManager
startUpdatingLocation];locationManager.delegate
=
self;
locationManager.distanceFilter
=
kCLDistanceFilterNone;
locationManager.desiredAccuracy
=
kCLLocationAccuracyBest;
}
63

64. Using the Core Location
 We need implement this:
-­‐ (void)locationManager:(CLLocationManager
*)manager
didUpdateToLocation:
(CLLocation
*)newLocation
fromLocation:(CLLocation
*)oldLocation
{
NSString
*latitudeString
=
[[NSString
alloc]
initWithFormat:@"%g°",
newLocation.coordinate.latitude];
latitudeLabel.text
=
latitudeString;
[latitudeString
release];
NSString
*longitudeString
=
[[NSString
alloc]
initWithFormat:@"%g°",
newLocation.coordinate.longitude];
longitudeLabel.text
=
longitudeString;
[longitudeString
release];
}
64

65. Exercise

66. Demo
 Where I am?

67. Quartz
8

68. Coding a new view
#import
<UIKit/UIKit.h>
@interface
myView
:
UIView
{
CGPoint
myPoint;
int
x;
int
y;
}
@property
CGPoint
myPoint;
@property
int
x;
@property
int
y;
-­‐(void)draw;
@end
68

69. Coding a new view
@implementation
myView
@synthesize
myPoint;
@synthesize
x;
@synthesize
y;
-­‐(id)initWithCoder:(NSCoder
*)coder
{
if
(self
=
[super
initWithCoder:coder])
{
x=self.bounds.size.width
/
2;
y=self.bounds.size.height
/
2;
}
return
self;
}
-­‐(void)touchesBegan:(NSSet
*)touches
withEvent:(UIEvent
*)event{
UITouch
*t
=
[touches
anyObject];
CGPoint
point
=
[t
locationInView:t.view];
x
=
point.x;
y
=
point.y;
[self
setNeedsDisplay];
}
69

70. Coding a new view
-­‐
(void)draw{
CGContextRef
context
=
UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context,
[UIColor
colorWithRed:1.0f
green:0.0f
blue:0.0f
alpha:1.0f].CGColor);
CGRect
patito
=
CGRectMake
(x,y,10,10);CGContextAddEllipseInRect
(context,
patito);
CGContextDrawPath(context,
kCGPathFillStroke);
}
-­‐ (void)drawRect:(CGRect)rect
{
[self
draw];
}
70

71. Connecting the view
71

72. Exercise

73. openGL | ES
9

74. openGL | ES
74

75. Demo

76. Plist file
3.3

77. plist file
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN"
"http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>CFBundleDevelopmentRegion</key>
<string>en</string>
<key>CFBundleDisplayName</key>
<string>${PRODUCT_NAME}</string>
<key>CFBundleExecutable</key>
<string>${EXECUTABLE_NAME}</string>
<key>CFBundleIconFile</key>
<string>Icon.png</string>
<key>CFBundleIdentifier</key>
<string>com.yourcompany.${PRODUCT_NAME:identifier}</string>
77

78. plist file
<key>CFBundleInfoDictionaryVersion</key>
<string>6.0</string>
<key>CFBundleName</key>
<string>${PRODUCT_NAME}</string>
<key>CFBundlePackageType</key>
<string>APPL</string>
<key>CFBundleSignature</key>
<string>????</string>
<key>CFBundleVersion</key>
<string>1.0</string>
<key>UIStatusBarHidden</key>
<true/>
<key>NSMainNibFile</key>
<string>MainWindow</string>
</dict>
</plist>
78

79. Exercises and
References
6

80. iPhone Dev Center
http://developer.apple.com/iphone
80

81. Instructors
Javier González Sánchez
Tecnológico de Monterrey, campus Guadalajara
javiergs@itesm.mx
.com/in/javiergs
Maria Elena Chávez Echeagaray
Tecnológico de Monterrey, campus Guadalajara
mechavez@itesm.mx
.com/in/mechavez
81