1. Getting Started
Day 1

2. Where we’re headed:
‣Hello World
‣Xcode
‣About Objective-C
‣Syntax
‣Types
‣Operators
‣Classes & Objects Part 1
‣Fraction Calculator App

3. The Fraction Calculator
‣ Work with basic data
types
‣ Work with simple
objects and a simple
object model
‣ Basic MVC architecture
‣ Build a basic UI with
interface builder

4. Hello World

5. #import <Foundation/Foundation.h>
int main (int argc, const char * argv[]) {
NSAutoreleasePool * pool =
[[NSAutoreleasePool alloc] init];
// insert code here...
NSLog(@"Hello, World!");
[pool drain];
return 0;
}
Hello World Example

6. Brief Xcode Tour

7. Starting a new project

8. The main window

9. The Console

10. Debug Window

11. Objective-C Basics

12. What is Objective-C
‣ An orthogonal superset over C
‣ Orthogonal = doesn’t override any C
functionality (almost)
‣ Object oriented
‣ Syntax a mix of SmallTalk and C
‣ Can be statically or dynamically typed

13. Objective-C Filetypes
‣ .xcodeproj - Your project bundle
‣ .h - header file
‣ .c - a C source file
‣ .m - an Objective-C source file
‣ .plist - a property list file

14. Syntax
‣ All statements end with a semi-colon
‣ Blocks (lower case ‘b’) are denoted by curly braces
‣ Comments:
‣ // in-line comment
‣ /* . . . . */ block comment
‣ # pre-processor directive

15. Syntax
Function Definition
int cube (int num)
{
return num * num;
}
Function Calls
cube (10);
Declaring Variables
int value = 10;

16. C Types
‣ Basic Types
‣ Int - an integer
‣ Float - decimal number
‣ Double - double precision decimal number
‣ Char - a single ASCII character (1 byte)
‣ Void - nothing (a variable cannot be declared void)
‣ Variations
‣ Signed / Unsigned (for ints)
‣ Long, long long (32 or 64 bits)
‣ Short (16 bits)
‣ Casting
‣ ( type ) variable

17. Objective-C Additions
‣ BOOL - boolean
‣ YES or NO
‣ id - pointer type for an objective-c object
‣ nil - the null value for objective-c

18. Esoteric Types
Struct
struct CGPoint {
CGFloat x;
CGFloat y;
};
Union
union aNumber {
int i;
float f;
}
Enum
enum CGRectEdge {
CGRectMinXEdge,
CGRectMinYEdge,
CGRectMaxXEdge,
CGRectMaxYEdge
};

19. Esoteric Types
Basic Typedef
typedef long NSInteger;
With a struct or enum
typedef struct {
CGFloat x;
CGFloat y;
} CGPoint;

20. Operators
‣ Arithmetic
‣ + addition
‣ - subtraction
‣ * multiplication
‣ / division
‣ % modulus
‣ Unary
‣ ++ increment
‣ -- decrement

21. Operators
‣ Assignment
‣ = simple assignment
‣ += add to
‣ -= subtract from
‣ *= multiply by
‣ /= divide by

22. Operators
‣ Logical
‣ == - equal to
‣ != - not equal to
‣ <, > - less than, greater than
‣ <=, >= - less than or equal, greater than or equal
‣ && - logical AND
‣ || - logical OR
‣ Pointers and References
‣ * - dereference
‣ & - reference (address of)

23. OO Syntax
‣ The ‘@’ symbol
‣ Used to create NSStrings
‣ Used as a prefix to obj-c keywords
‣ Calling Object Methods
[[NSAutoreleasePool alloc] init];
[NSDictionary dictionaryWithObject:@"foo" forKey:@"bar"];

24. Loops
For loop
for (int i = 0; i < 100; i++)
{
/* statements */
}
While loop
while (condition)
{
/* statements */
}
Do ... While loop
do {
/* statements */
} while (condition);

25. Branching
If ... else if ... else
if (condition)
{
/* statements */
}
else if (anotherCondition)
{
/* statements */
}
else
{
/* statements */
}

26. Branching
Switch
switch (expression)
{
case aConstant:
/* statements */
break;
case anotherConst:
/* statements */
break;
default:
/* statements */
break;
}
Ternary Operator
int value = condition ? 10 : 20;

27. Classes and Objects

28. What Defines an Object
‣Actions
‣Properties

29. A Car Object
‣ Properties
‣ Make
‣ Model
‣ Year
‣ Color
‣ Actions
‣ Accelerate
‣ Lock
‣ Steer

30. Objective-c Objects
‣ Data and Interface
Data Interface Message
‣Messages are sent to Objects
‣Objects may respond to messages

31. Messaging
‣ Messages are sent to objects
‣ Different than calling a method
‣ Messages are referred to as selectors
‣ The object knows its type and will respond
accordingly.
‣ All selectors are “virtual”
‣ Objects may respond to messages
‣ If the selector doesn’t exist (is unrecognized) an
exception is typically thrown.

32. Sample Class Interface
@interface MyClass : NSObject
{
int value
id someData
NSString *name
}
- (id)initWithName:(NSString *)name;
+ (MyClass *)createWithName:(NSString *)name;
@end

33. Sample Class Implementation
@implementation MyClass
- (id)initWithName:(NSString *)aname
{
self = [super init];
if (self)
{
name = [aname copy];
}
return self
}
+ (MyClass *)createWithName:(NSString *)name
{
return [[[self alloc] initWithName:name] autorelease];
}
@end

34. Named Properties
Named Property Declaration
@property (nonatomic, retain) NSString *name;
@property (nonatomic, assign) int value;
Interface Implementation
@synthesize name, value;
At compile time, the @synthesize produces getters
and setters.

35. Sample Class Interface
@interface MyClass : NSObject
{
int value
id someData
NSString *name
}
- (id)initWithName:(NSString *)name;
+ (MyClass *)createWithName:(NSString *)aname;
@property (nonatomic, retain) NSString *name;
@property (nonatomic, assign) int value;
@end

36. Sample Class Implementation
@implementation MyClass
@synthesize name, value;
- (id)initWithName:(NSString *)aname
{
self = [super init];
if (self)
{
name = [aname copy];
}
return self
}
+ (MyClass *)createWithName:(NSString *)name
{
return [[[self alloc] initWithName:name] autorelease];
}

37. Fraction Calculator

38. Project Overview
‣ Fraction Class
‣ Calculator Class
‣ View Controller
‣ UI File (.xib)

39. Architecture
View
Xib file Calculator
Controller
Fraction
View Controller “Model”

40. The Fraction Class
‣ Properties
‣ Numerator
‣ Denominator
‣ Actions
‣ Create
‣ Set properties
‣ Add, Subtract fractions
‣ Multiply, Divide fractions
‣ Reduce

41. Fraction Interface
@interface Fraction : NSObject
{
int numerator;
int denominator;
}
- (id)initWithNumerator:(int)num denominator:(int)denom;
- (double)asDecimal;
- (Fraction *)add:(Fraction *)fraction;
- (Fraction *)subtract:(Fraction *)fraction;
- (Fraction *)multiply:(Fraction *)fraction;
- (Fraction *)divide:(Fraction *)fraction;
- (void)reduce;
@property (nonatomic, assign) int numerator;
@property (nonatomic, assign) int denominator;
@end

42. Fraction Implementation
#import "Fraction.h"
@implementation Fraction
@synthesize numerator;
@synthesize denominator;

43. Fraction Implementation
- (id)initWithNumerator:(int)num denominator:(int)denom
{
if (self = [super init])
{
numerator = num;
denominator = denom != 0 ? denom : 1;
}
return self;
}
- (NSString *)description
{
return [NSString stringWithFormat:@"Fraction: %d/%d", numerator,
denominator];
}

44. Fraction Implementation
- (void)setDenominator:(int)denom
{
if (denom != 0)
{
denominator = denom;
}
else
{
denominator = 1;
}
}
- (double)asDecimal
{
return (double)numerator / denominator;
}

45. Fraction Implementation
// page 144
- (Fraction *)add:(Fraction *)fraction
{
int resultNum, resultDenom;
resultNum = numerator * fraction.denominator
+ denominator * fraction.numerator;
resultDenom = denominator * fraction.denominator;
Fraction *result = [[Fraction alloc] initWithNumerator:resultNum
denominator:resultDenom];
[result reduce];
return result;
}

46. Fraction Implementation
- (Fraction *)subtract:(Fraction *)fraction
{
Fraction *tmp = [[Fraction alloc] initWithNumerator:
-fraction.numerator
denominator:fraction.denominator];
Fraction *result = [self add:tmp];
[tmp release];
return result;
}

47. Fraction Implementation
- (Fraction *)multiply:(Fraction *)fraction
{
int resultNum, resultDenom;
resultNum = numerator * fraction.numerator;
resultDenom = denominator * fraction.denominator;
Fraction *result = [[Fraction alloc] initWithNumerator:resultNum
denominator:resultDenom];
[result reduce];
return result;
}

48. Fraction Implementation
- (Fraction *)divide:(Fraction *)fraction
{
Fraction *tmp = [[Fraction alloc] initWithNumerator:fraction.denominator
denominator:fraction.numerator];
Fraction *result = [self multiply:tmp];
[tmp release];
return result;
}

49. Fraction Implementation
// page 146
- (void)reduce
{
int tmpNum = numerator;
int tmpDen = denominator;
int temp = 0;
while (tmpDen != 0)
{
temp = tmpNum % tmpDen;
tmpNum = tmpDen;
tmpDen = temp;
}
numerator /= tmpNum;
denominator /= tmpNum;
}

50. Calculator Class
‣ Properties
‣ An operation to perform
‣ 2 operands
‣ A result of an operation
‣ Actions
‣ Set properties
‣ Perform an operation

51. Calculator Interface
#import "Fraction.h"
typedef enum
{
CalcOpAdd,
CalcOpMul,
CalcOpDiv,
CalcOpSub
} CalculatorOperation;
@interface Calculator : NSObject
{
Fraction *operand1;
Fraction *operand2;
Fraction *result;
}
- (void)performOperation:(CalculatorOperation)op;
- (void)reset;
@property (nonatomic, retain) Fraction *operand1, *operand2;
@property (nonatomic, readonly) Fraction *result;
@end

52. Calculator Implementation
#import "Calculator.h"
@implementation Calculator
@synthesize operand1, operand2, result;
- (void)dealloc
{
[operand1 release];
[operand2 release];
[result release];
[super dealloc];
}

53. Calculator Implementation
- (void)performOperation:(CalculatorOperation)op
{
switch (op) {
case CalcOpAdd:
result = [operand1 add:operand2];
break;
case CalcOpSub:
result = [operand1 subtract:operand2];
break;
case CalcOpMul:
result = [operand1 multiply:operand2];
break;
case CalcOpDiv:
result = [operand1 divide:operand2];
break;
default:
break;
}
}

54. Calculator Implementation
- (void)reset
{
self.operand1 = nil;
self.operand2 = nil;
[result release];
result = nil;
}
@end

55. View Controller
‣ Subclass of UIViewController
‣ Properties
‣ View
‣ Actions
‣ Respond to UI Events
‣ Manipulate UI Elements
‣ As a subclass of UIViewController, many functions
are provided already.

56. VC Interface
@interface FractionCalculatorViewController : UIViewController
{
UILabel *display;
NSMutableString *displayString;
Calculator *calculator;
CalculatorOperation op;
BOOL workingNumerator;
BOOL workingFirstNumber;
}

57. VC Interface
- (IBAction)numberButtonTap:(UIButton *)sender;
- (IBAction)opButtonTap:(UIButton *)sender;
- (IBAction)overButtonTap:(UIButton *)sender;
- (IBAction)clearButtonTap:(UIButton *)sender;
- (IBAction)equalsButtonTap:(UIButton *)sender;
@property (nonatomic, retain) IBOutlet UILabel *display;
@property (nonatomic, retain) NSMutableString *displayString;

58. VC Interface
typedef enum {
OperatorButtonTagAdd = 10,
OperatorButtonTagSub = 11,
OperatorButtonTagMul = 12,
OperatorButtonTagDiv = 13
} OperatorButtonTag;

59. VC Implementation
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
if ((self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]))
{
calculator = [[Calculator alloc] init];
displayString = [[NSMutableString alloc] init];
workingNumerator = YES;
workingFirstNumber = YES;
}
return self;
}
- (void)dealloc
{
[display release];
[displayString release];
[calculator release];
[super dealloc];
}

60. VC Implementation
- (IBAction)numberButtonTap:(UIButton *)sender
{
[displayString appendString:[NSString stringWithFormat:@"%d", [sender tag]]];
Fraction *f;
if (workingFirstNumber)
{
if (calculator.operand1 == nil)
{
calculator.operand1 = [[Fraction alloc] init];
}
f = calculator.operand1;
}
else
{
if (calculator.operand2 == nil)
{
calculator.operand2 = [[Fraction alloc] init];
}
f = calculator.operand2;
}

61. VC Implementation
if (workingNumerator)
{
f.numerator *= 10;
f.numerator += [sender tag];
}
else
{
f.denominator *= 10;
f.denominator += [sender tag];
}
[display setText:displayString];
}

62. VC Implementation
- (IBAction)opButtonTap:(UIButton *)sender
{
switch ([sender tag])
{
case OperatorButtonTagAdd:
op = CalcOpAdd;
[displayString appendString:[NSString stringWithFormat:@" + "]];
break;
case OperatorButtonTagSub:
op = CalcOpSub;
[displayString appendString:[NSString stringWithFormat:@" - "]];
break;
case OperatorButtonTagMul:
op = CalcOpMul;
[displayString appendString:[NSString stringWithFormat:@" x "]];
break;
case OperatorButtonTagDiv:
op = CalcOpDiv;
[displayString appendString:[NSString stringWithFormat:@" ÷ "]];
break;
default:
break;
}
workingFirstNumber = NO;
workingNumerator = YES;
[display setText:displayString];
}

63. VC Implementation
- (IBAction)clearButtonTap:(UIButton *)sender
{
workingFirstNumber = YES;
workingNumerator = YES;
calculator.operand1 = nil;
calculator.operand2 = nil;
[displayString setString:@""];
[display setText:displayString];
}
- (IBAction)overButtonTap:(UIButton *)sender
{
[displayString appendString:@" / "];
[display setText:displayString];
workingNumerator = NO;
}

64. VC Implementation
- (IBAction)equalsButtonTap:(UIButton *)sender
{
NSLog(@"%@ %@", calculator.operand1, calculator.operand2);
[calculator performOperation:op];
[displayString setString:[NSString stringWithFormat:@"%d / %d", calculator.result.numerator,
calculator.result.denominator]];
[display setText:displayString];
}
- (void)dealloc
{
[display release];
[displayString release];
[calculator release];
[super dealloc];
}

65. UIApplication Delegate
‣ Handles application after initial load.
‣ Houses the view controller

66. Application Delegate
- (BOOL)application:(UIApplication *)application
didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// Override point for customization after application launch.
mainViewController = [[FractionCalculatorViewController alloc]
initWithNibName:@"FractionCalculatorViewController"
bundle:nil];
[window addSubview:mainViewController.view];
[window makeKeyAndVisible];
return YES;
}

67. Creating the fraction UI

68. UI Files are xib files

69. Object Properties Object Library