I gave this talk at iPhone Dev Con in Boston, April 2011.

1. iPhone for .NET Developers
Ben Scheirman
Director of Development - ChaiONE
@subdigital

2. Slide 1 of 429

4. What you need
A Mac
Xcode
iPhone SDK (limited to Simulator)
iPhone Developer Program ($99 /year)

5. Objective-C
Based on C
Object Oriented
Dynamic
A little weird
Powerful

6. Objective-C Primer
Calling methods

7. Objective-C Primer
Calling methods
[someObject someMethod];

8. Objective-C Primer
Calling methods
[someObject someMethod];
[someObject someMethodWithInput:5];

9. Objective-C Primer
Calling methods
[someObject someMethod];
[someObject someMethodWithInput:5];
[dictionary setObject:obj
forKey:key];

10. Objective-C Primer
Nesting method calls

11. Objective-C Primer
Nesting method calls
[NSString stringWithFormat:
[prefs format]];

12. Objective-C Primer
Instantiating classes

13. Objective-C Primer
Instantiating classes
UIView *view = [[UIView alloc] init];

14. Objective-C Primer
Instantiating classes
UIView *view = [[UIView alloc] init];
NSDate *date = [NSDate date];

15. Objective-C Primer
Defining Classes

16. Objective-C Primer
Defining Classes
//Person.h
@interface Person {
//instance variables
}
//properties & methods
@end

17. Objective-C Primer
Defining Classes

18. Objective-C Primer
Defining Classes
//Person.m
#import "Person.h"
@implementation Person
//implement properties & methods
@end

19. Objective-C Primer
Defining Methods

20. Objective-C Primer
Defining Methods
-(void)showLoadingText:(NSString *)text animated:(BOOL)animated;

21. Objective-C Primer
Defining Methods
Method name (selector)
-(void)showLoadingText:(NSString *)text animated:(BOOL)animated;

22. Objective-C Primer
Defining Methods
Method name (selector)
-(void)showLoadingText:(NSString *)text animated:(BOOL)animated;
Return Type

23. Objective-C Primer
Defining Methods
Method name (selector)
-(void)showLoadingText:(NSString *)text animated:(BOOL)animated;
Return Type
Instance method

24. Objective-C Primer
Defining Methods
Method name (selector)
-(void)showLoadingText:(NSString *)text animated:(BOOL)animated;
Return Type
Parameters
Instance method

25. Other interesting Things
nil is a no-op
Foo *foo = nil;
[foo doSomething]; //nothing happens
NSArray *array = nil;
[array count]; //returns 0

26. Other Interesting Things
Mix-in C style method definitions
// I put this in Macros.h
static inline BOOL isEmpty(id thing) {
return thing == nil
|| ([thing respondsToSelector:@selector(length)]
&& [(NSData *)thing length] == 0)
|| ([thing respondsToSelector:@selector(count)]
&& [(NSArray *)thing count] == 0);
}
this method comes from Wil Shipley

27. Other Interesting Things
Dynamic Programming achieved through Key-Value
Coding
NSArray *items = [NSArray arrayWithObject:foo];
[items valueForKey:@"count"]; //returns 1

28. Other Interesting Things
Can achieve "Extension Methods" or "Mix-ins" via
Objective-C Categories
//NSString+MyAdditions.h
@interface NSString (MyAdditions)
-(NSString *)stringInReverse;
@end
//NSString+MyAdditions.m
@implementation NSString (MyAdditions)
-(NSString *)stringInReverse { ... }
@end
//usage
#import "NSString+MyAdditions.h"
[@"foxy" stringInReverse]; //returns @"yxof"

29. Memory Management
No garbage collection on the iPhone
Retain / Release

30. Memory Management
Retain / Release Dance

31. Memory Management
Retain / Release Dance
1
Foo *foo = [[Foo alloc] init];

32. Memory Management
Retain / Release Dance
1
Foo *foo = [[Foo alloc] init];
2
[foo retain];

33. Memory Management
Retain / Release Dance
1
Foo *foo = [[Foo alloc] init];
2
[foo retain];
1
[foo release];

34. Memory Management
Retain / Release Dance
1
Foo *foo = [[Foo alloc] init];
2
[foo retain];
1
[foo release];
[foo release]; 0

35. Memory Management
Retain / Release Dance
1
Foo *foo = [[Foo alloc] init];
2
[foo retain];
1
[foo release];
[foo release]; foo is deallocated 0

36. Forgetting to release (over-retaining)
Your
Class

37. Forgetting to release (over-retaining)
1
alloc/init
Your
Object
Class

38. Forgetting to release (over-retaining)
2
1
alloc/init
retain
Your
Object
Class

39. Forgetting to release (over-retaining)
2
1
alloc/init
retain
Your
doSomething Object
Class

40. Forgetting to release (over-retaining)
1
alloc/init
retain
Your
doSomething Object
Class
release

41. Forgetting to release (over-retaining)
1
Object

42. Forgetting to release (over-retaining)
1
Object Object is leaked
App doesn't crash

43. Over-releasing
Your
Class

44. Over-releasing
1
alloc/init
Your
Object
Class

45. Over-releasing
alloc/init
release
Your Garbage
Class Memory

46. Over-releasing
alloc/init
release
Your Garbage
Class
doSomething
Memory App Crashes

47. Getters / Setters

48. Getters / Setters
[foo setBar:@"baz"];

49. Getters / Setters
[foo setBar:@"baz"];
[foo bar]; //returns @"baz"

50. Getters / Setters
[foo setBar:@"baz"];
[foo bar]; //returns @"baz"
foo.bar = @"gruul";

51. Getters / Setters
[foo setBar:@"baz"];
[foo bar]; //returns @"baz"
foo.bar = @"gruul";
foo.bar //returns @"gruul"

52. Implementing setters

53. Implementing setters
-(void)setBar:(id)value {

54. Implementing setters
-(void)setBar:(id)value {
if(bar == value) return;

55. Implementing setters
-(void)setBar:(id)value {
if(bar == value) return;
[bar release];

56. Implementing setters
-(void)setBar:(id)value {
if(bar == value) return;
[bar release];
bar = nil;

57. Implementing setters
-(void)setBar:(id)value {
if(bar == value) return;
[bar release];
bar = nil;
if(value != nil)

58. Implementing setters
-(void)setBar:(id)value {
if(bar == value) return;
[bar release];
bar = nil;
if(value != nil)
bar = [value retain];

59. Implementing setters
-(void)setBar:(id)value {
if(bar == value) return;
[bar release];
bar = nil;
if(value != nil)
bar = [value retain];
}

60. No Thanks

61. Properties

62. Properties
//Foo.h

63. Properties
//Foo.h
@property (nonatomic, retain) UIImage *image;

64. Properties
//Foo.h
@property (nonatomic, retain) UIImage *image;
@property (nonatomic, copy) NSString *message;

65. Properties
//Foo.h
@property (nonatomic, retain) UIImage *image;
@property (nonatomic, copy) NSString *message;
//Foo.m

66. Properties
//Foo.h
@property (nonatomic, retain) UIImage *image;
@property (nonatomic, copy) NSString *message;
//Foo.m
@synthesize image, message;

67. Properties
//Foo.h
@property (nonatomic, retain) UIImage *image;
@property (nonatomic, copy) NSString *message;
//Foo.m
@synthesize image, message;
-(void)dealloc {

68. Properties
//Foo.h
@property (nonatomic, retain) UIImage *image;
@property (nonatomic, copy) NSString *message;
//Foo.m
@synthesize image, message;
-(void)dealloc {
[image release];

69. Properties
//Foo.h
@property (nonatomic, retain) UIImage *image;
@property (nonatomic, copy) NSString *message;
//Foo.m
@synthesize image, message;
-(void)dealloc {
[image release];
[message release];

70. Properties
//Foo.h
@property (nonatomic, retain) UIImage *image;
@property (nonatomic, copy) NSString *message;
//Foo.m
@synthesize image, message;
-(void)dealloc {
[image release];
[message release];
[super dealloc];

71. Properties
//Foo.h
@property (nonatomic, retain) UIImage *image;
@property (nonatomic, copy) NSString *message;
//Foo.m
@synthesize image, message;
-(void)dealloc {
[image release];
[message release];
[super dealloc];
}

72. Dot Syntax Dogma
Use dot syntax if you like it
Just be aware of what it's hiding

73. Xcode
Your IDE
Code completion
Interactive Debugger
Lacks good refactoring tools

74. Interface Builder
Now Part of Xcode 4
Drag-n-drop UI building
Layouts are defined in XIBs (XML representation).
Usually called "Nibs"
"Make connections" with classes defined in Xcode
variables --> UI components
UI events --> methods

75. Instruments
Find Memory Leaks
Analyze Memory Usage
Track down slow code

76. iOS SDK
Accelerate CoreMotion
AddressBook CoreTelephony
AudioToolbox CoreText
Your app
AVFoundation CoreVideo
UIKit CoreAudio GameKit
CoreFoundation CoreData iAd
CoreGraphics CoreLocation MapKit
CFNetwork StoreKit

77. Model View Controller
Model View
Controller

78. The View Controller
Handles setup logic for a screen
Handles user input
Interacts with the model
Contains 1 or more views

79. The View
Visual representation
Drawing
Laying out subviews (autorotation)
May Handle touch events

80. Lifecycle of an App
main.m

81. Lifecycle of an App
main.m
UIApplication

82. Lifecycle of an App
main.m
UIApplication

83. Lifecycle of an App
main.m MainWindow.xib
UIApplication

84. Lifecycle of an App
main.m MainWindow.xib
UIApplication

85. Lifecycle of an App
main.m MainWindow.xib
UIApplication YourAppDelegate
UIWindow Root View Controller

86. Lifecycle of an App
main.m MainWindow.xib
UIApplication YourAppDelegate
applicationDidFinishLaunching
UIWindow Root View Controller

87. Time to code!