My slides for the FWT meetup on 4/11/12

1. iOS 5

2. iOS 5
• About Me:
• Pat Zearfoss
• Mindgrub Technologies, LLC
• BS Computer Science - UMBC 2008
• Working with mobile and iOS for 4
years.

3. iOS 5
• Web:
pzearfoss@gmail.com
http://zearfoss.wordpress.com
@pzearfoss
http://www.github.com/pzearfoss

4. Where we’re going:

5. Where we’re going:
• Quick Objective-c and iOS review

6. Where we’re going:
• Quick Objective-c and iOS review
• Overview of iOS 5 additions and changes

7. Where we’re going:
• Quick Objective-c and iOS review
• Overview of iOS 5 additions and changes
• Introducing Lobstagram

8. Where we’re going:
• Quick Objective-c and iOS review
• Overview of iOS 5 additions and changes
• Introducing Lobstagram
• Other iOS 5 features (as time permits)

9. About iOS Development

10. About iOS Development
• Objective-c only

11. About iOS Development
• Objective-c only
• Other tools are getting better:

12. About iOS Development
• Objective-c only
• Other tools are getting better:
• Titanium, PhoneGap, MonoTouch

13. About iOS Development
• Objective-c only
• Other tools are getting better:
• Titanium, PhoneGap, MonoTouch
• Mac required

14. About iOS Development
• Objective-c only
• Other tools are getting better:
• Titanium, PhoneGap, MonoTouch
• Mac required
• Xcode required (free!)

15. Xcode
• Download from App Store

16. Objective-c crash
course

17. Getting Started

18. Getting Started
• Things you should know

19. Getting Started
• Things you should know
• Classical OO

20. Getting Started
• Things you should know
• Classical OO
• Classes

21. Getting Started
• Things you should know
• Classical OO
• Classes
• Inheritance

22. Getting Started
• Things you should know
• Classical OO
• Classes
• Inheritance
• Polymorphism

23. Getting Started

24. Getting Started
• Recommended but not required

25. Getting Started
• Recommended but not required
• Some knowledge of C

26. Getting Started
• Recommended but not required
• Some knowledge of C
• malloc() . . . free() ?

27. Getting Started
• Recommended but not required
• Some knowledge of C
• malloc() . . . free() ?
• Some knowledge of design patterns:

28. Getting Started
• Recommended but not required
• Some knowledge of C
• malloc() . . . free() ?
• Some knowledge of design patterns:
• MVC, Singleton, Delegation

29. About Objective-C

30. About Objective-C
• Object Oriented superset over C

31. About Objective-C
• Object Oriented superset over C
Standard C

32. About Objective-C
• Object Oriented superset over C
Standard C
Objective-C

33. About Objective-C
• Object Oriented superset over C
Standard C
Objective-C
• Anything that works in C will work in
Objective-C

34. Obj-C in 10 minutes

35. Obj-C in 10 minutes
• All the things you know from C

36. Obj-C in 10 minutes
• All the things you know from C
• Variables are typed:

37. Obj-C in 10 minutes
• All the things you know from C
• Variables are typed:
• int, float, double, char

38. Obj-C in 10 minutes
• All the things you know from C
• Variables are typed:
• int, float, double, char
int foo = 5;

39. Obj-C in 10 minutes
• All the things you know from C
• Variables are typed:
• int, float, double, char
int foo = 5;
• Separate compilation

40. Obj-C in 10 minutes
• All the things you know from C
• Variables are typed:
• int, float, double, char
int foo = 5;
• Separate compilation
• .h for interface declaration

41. Obj-C in 10 minutes
• All the things you know from C
• Variables are typed:
• int, float, double, char
int foo = 5;
• Separate compilation
• .h for interface declaration
• .m for implementation (instead of .c)

42. Obj-C in 10 minutes

43. Obj-C in 10 minutes
• Functions / Methods have return types and
typed arguments

44. Obj-C in 10 minutes
• Functions / Methods have return types and
typed arguments
int sumOfItems(int i, int j)
{
return i + j;
}

45. Obj-C in 10 minutes
• Functions / Methods have return types and
typed arguments
int sumOfItems(int i, int j)
{
return i + j;
}
• Other types

46. Obj-C in 10 minutes
• Functions / Methods have return types and
typed arguments
int sumOfItems(int i, int j)
{
return i + j;
}
• Other types
• void, NULL

47. Obj-C in 10 minutes
• Functions / Methods have return types and
typed arguments
int sumOfItems(int i, int j)
{
return i + j;
}
• Other types
• void, NULL
• pointers to types (int *, void *)

48. Obj-C in 10 minutes

49. Obj-C in 10 minutes
• Objective-C Additions:

50. Obj-C in 10 minutes
• Objective-C Additions:
• BOOL - YES / NO

51. Obj-C in 10 minutes
• Objective-C Additions:
• BOOL - YES / NO
BOOL isSet = YES;

52. Obj-C in 10 minutes
• Objective-C Additions:
• BOOL - YES / NO
BOOL isSet = YES;
• id - strictly a pointer to an object

53. Obj-C in 10 minutes
• Objective-C Additions:
• BOOL - YES / NO
BOOL isSet = YES;
• id - strictly a pointer to an object
• nil - a zero’d out pointer

54. Obj-C in 10 minutes
• Objective-C Additions:
• BOOL - YES / NO
BOOL isSet = YES;
• id - strictly a pointer to an object
• nil - a zero’d out pointer
• nil != (necessarily) NULL or 0

55. Obj-C in 10 minutes

56. Obj-C in 10 minutes
• Classes

57. Obj-C in 10 minutes
• Classes
• Exist as a class pair

58. Obj-C in 10 minutes
• Classes
• Exist as a class pair
• Instance variables and instance methods act
on an instance object

59. Obj-C in 10 minutes
• Classes
• Exist as a class pair
• Instance variables and instance methods act
on an instance object
• Class (static) methods act on the class
object

60. Obj-C in 10 minutes
• Classes
• Exist as a class pair
• Instance variables and instance methods act
on an instance object
• Class (static) methods act on the class
object
• There is only ever one class object at any
given time

61. Obj-C in 10 minutes
• Classes
• Exist as a class pair
• Instance variables and instance methods act
on an instance object
• Class (static) methods act on the class
object
• There is only ever one class object at any
given time
• Class variables really don’t exist

62. Obj-C in 10 minutes
• Classes
#import <Foundation/Foundation.h>
@interface MyClass : NSObject
{
id aChildObject;
NSArray *someItems;
}
+ (NSString *)className;
- (void)logMe;
@property (nonatomic, retain) id aChildObject;
@end

63. Obj-C in 10 minutes
• Classes Include a header
#import <Foundation/Foundation.h>
file
@interface MyClass : NSObject
{
id aChildObject;
NSArray *someItems;
}
+ (NSString *)className;
- (void)logMe;
@property (nonatomic, retain) id aChildObject;
@end

64. Obj-C in 10 minutes
• Classes
#import <Foundation/Foundation.h>
Declare interface
@interface MyClass : NSObject extends
{
NSObject
id aChildObject;
NSArray *someItems;
}
+ (NSString *)className;
- (void)logMe;
@property (nonatomic, retain) id aChildObject;
@end

65. Obj-C in 10 minutes
• Classes
#import <Foundation/Foundation.h>
@interface MyClass : NSObject
{
id aChildObject; Class instance
NSArray *someItems; variables
}
+ (NSString *)className;
- (void)logMe;
@property (nonatomic, retain) id aChildObject;
@end

66. Obj-C in 10 minutes
• Classes
#import <Foundation/Foundation.h>
@interface MyClass : NSObject
{
id aChildObject;
NSArray *someItems;
}
+ (NSString *)className;
A class (static)
- (void)logMe; method
@property (nonatomic, retain) id aChildObject;
@end

67. Obj-C in 10 minutes
• Classes
#import <Foundation/Foundation.h>
@interface MyClass : NSObject
{
id aChildObject;
NSArray *someItems;
}
+ (NSString *)className;
- (void)logMe; An instance
method
@property (nonatomic, retain) id aChildObject;
@end

68. Obj-C in 10 minutes
• Classes
#import <Foundation/Foundation.h>
@interface MyClass : NSObject
{
id aChildObject;
NSArray *someItems;
}
A declared
+ (NSString *)className; property
- (void)logMe;
@property (nonatomic, retain) id aChildObject;
@end

69. Obj-C in 10 minutes
• Classes
#import <Foundation/Foundation.h>
@interface MyClass : NSObject
{
id aChildObject;
NSArray *someItems;
}
+ (NSString *)className;
- (void)logMe;
@property (nonatomic, retain) id aChildObject;
Close the
@end
interface block

70. Obj-C in 10 minutes
• Classes
#import <Foundation/Foundation.h>
@interface MyClass : NSObject
{
id aChildObject;
NSArray *someItems;
}
+ (NSString *)className;
- (void)logMe;
@property (nonatomic, retain) id aChildObject;
@end

71. Obj-C in 10 minutes
• Classes
#import "MyClass.h"
@implementation MyClass
@synthesize aChildObject;
- (id)init
{
self = [super init];
if (self)
{
someItems = [[NSArray alloc] init];
}
return self;
}

72. Obj-C in 10 minutes
• Classes
#import "MyClass.h"
Include a header
file
@implementation MyClass
@synthesize aChildObject;
- (id)init
{
self = [super init];
if (self)
{
someItems = [[NSArray alloc] init];
}
return self;
}

73. Obj-C in 10 minutes
• Classes
#import "MyClass.h"
Begin
@implementation MyClass implementation
@synthesize aChildObject; block
- (id)init
{
self = [super init];
if (self)
{
someItems = [[NSArray alloc] init];
}
return self;
}

74. Obj-C in 10 minutes
• Classes
#import "MyClass.h"
@implementation MyClass
@synthesize aChildObject;
Auto-generate
property
- (id)init
{
self = [super init];
if (self)
{
someItems = [[NSArray alloc] init];
}
return self;
}

75. Obj-C in 10 minutes
• Classes
#import "MyClass.h"
@implementation MyClass
@synthesize aChildObject;
- (id)init Initializer
{ (constructor)
self = [super init];
if (self)
{
someItems = [[NSArray alloc] init];
}
return self;
}

76. Obj-C in 10 minutes
• Classes
#import "MyClass.h"
@implementation MyClass
@synthesize aChildObject;
- (id)init
{
self = [super init];
if (self)
{
someItems = [[NSArray alloc] init];
}
return self;
}

77. Obj-C in 10 minutes
• Classes
#import "MyClass.h"
@implementation MyClass
@synthesize aChildObject;
- (id)init
{
self = [super init];
Call to super
if (self) class
{
someItems = [[NSArray alloc] init];
}
return self;
}

78. Obj-C in 10 minutes
• Classes
#import "MyClass.h"
@implementation MyClass
@synthesize aChildObject;
- (id)init
{
self = [super init]; “new” an array
if (self)
{
someItems = [[NSArray alloc] init];
}
return self;
}

79. Obj-C in 10 minutes
• Classes
#import "MyClass.h"
@implementation MyClass
@synthesize aChildObject;
- (id)init
{
self = [super init];
if (self)
{
someItems = [[NSArray alloc] init];
}
return self;
}

80. Obj-C in 10 minutes
• Continued . . .
- (void)dealloc
{
[aChildObject release];
[someItems release];
[super dealloc];
}
- (void)logMe
{
NSLog(@"MyClass");
}
+ (NSString *)className
{
return NSStringFromClass([self class]);
}
@end

81. Obj-C in 10 minutes
• Continued . . .
- (void)dealloc
{ Destructor
[aChildObject release];
[someItems release];
[super dealloc];
}
- (void)logMe
{
NSLog(@"MyClass");
}
+ (NSString *)className
{
return NSStringFromClass([self class]);
}
@end

82. Obj-C in 10 minutes
• Continued . . .
- (void)dealloc
{
[aChildObject release];
[someItems release];
[super dealloc];
}
- (void)logMe
Instance method
{ implementation
NSLog(@"MyClass");
}
+ (NSString *)className
{
return NSStringFromClass([self class]);
}
@end

83. Obj-C in 10 minutes
• Continued . . .
- (void)dealloc
{
[aChildObject release];
[someItems release];
[super dealloc];
}
- (void)logMe
{
NSLog(@"MyClass"); Class method
} implementation
+ (NSString *)className
{
return NSStringFromClass([self class]);
}
@end

84. Obj-C in 10 minutes
• Continued . . .
- (void)dealloc
{
[aChildObject release];
[someItems release];
[super dealloc];
}
- (void)logMe
{
NSLog(@"MyClass");
}
+ (NSString *)className
{
return NSStringFromClass([self class]); End
}
implementation
@end block

85. Obj-C in 10 minutes
• Continued . . .
- (void)dealloc
{
[aChildObject release];
[someItems release];
[super dealloc];
}
- (void)logMe
{
NSLog(@"MyClass");
}
+ (NSString *)className
{
return NSStringFromClass([self class]);
}
@end

86. Obj-C in 10 minutes

87. Obj-C in 10 minutes
• What’s with all the ‘@’ and ‘[ ]’?

88. Obj-C in 10 minutes
• What’s with all the ‘@’ and ‘[ ]’?
•@
• Objective-C keywords
• Initializer for string constants

89. Obj-C in 10 minutes
• What’s with all the ‘@’ and ‘[ ]’?
•@
• Objective-C keywords
• Initializer for string constants
• ‘[]’
• “Send a message to an object”
• Like calling a method, but more dynamic

90. Obj-C in 10 minutes

91. Obj-C in 10 minutes
• Method Calls (messages)

92. Obj-C in 10 minutes
• Method Calls (messages)
• Names are intermixed with arguments:

93. Obj-C in 10 minutes
• Method Calls (messages)
• Names are intermixed with arguments:
• method definition
- (void)setItems:(NSArray *)items childObject:(id)obj;

94. Obj-C in 10 minutes
• Method Calls (messages)
• Names are intermixed with arguments:
• method definition
- (void)setItems:(NSArray *)items childObject:(id)obj;
• method call
[self setItems:[NSArray array] childObject:object];

95. Obj-C in 10 minutes
- (void)setItems:(NSArray *)items childObject:(id)obj;

96. Obj-C in 10 minutes
Return
Type
- (void)setItems:(NSArray *)items childObject:(id)obj;

97. Obj-C in 10 minutes
Return
Type
- (void)setItems:(NSArray *)items childObject:(id)obj;
Method Name

98. Obj-C in 10 minutes
Return
Type Arguments and Types
- (void)setItems:(NSArray *)items childObject:(id)obj;
Method Name

99. Obj-C in 10 minutes
[self setItems:[NSArray array] childObject:object];

100. Obj-C in 10 minutes
Receiver
[self setItems:[NSArray array] childObject:object];

101. Obj-C in 10 minutes
Receiver
[self setItems:[NSArray array] childObject:object];
Method Name

102. Obj-C in 10 minutes
Receiver Arguments
[self setItems:[NSArray array] childObject:object];
Method Name

103. Obj-C in 10 minutes

104. Obj-C in 10 minutes
• Protocols

105. Obj-C in 10 minutes
• Protocols
• Analogous to interfaces
@protocol MyProtocol <NSObject>
- (void)protocolMethod;
@property (nonatomic, retain) NSObject *anObject;
@end

106. Obj-C in 10 minutes
• Protocols
• Analogous to interfaces
@protocol MyProtocol <NSObject>
- (void)protocolMethod;
@property (nonatomic, retain) NSObject *anObject;
@end
• Adopting a protocol
@interface MyClass : NSObject <MyProtocol>

107. Obj-C in 10 minutes
• Categories - Something completely
different
• Add functionality to an existing class
@interface NSString (firstChar)
- (unichar)firstChar;
@end
@implementation NSString (reverse)
- (unichar)firstChar
{
return [self characterAtIndex:0];
}
@end

108. iOS in 10 Minutes

109. Key Objects

110. Key Objects
• UIViewController
• Contains a view, manages all the information and
widgets on the view.
• One Controller per view (screen)

111. Key Objects
• UIViewController
• Contains a view, manages all the information and
widgets on the view.
• One Controller per view (screen)
• UIView
• The view itself. All UI widgets inherit from
UIView.
• Objects on a view are “subviews” of that view

112. Key Patterns
MVC

113. Key Patterns
MVC
Model

114. Key Patterns
MVC
Model View

115. Key Patterns
MVC
Model Controller View

116. Key Patterns

117. Key Patterns
• Delegation (Datasource)

118. Key Patterns
• Delegation (Datasource)
• Alleviates subclassing

119. Key Patterns
• Delegation (Datasource)
• Alleviates subclassing
“I’m a table view. The user tapped the fourth cell.
Thought you should know.”

120. Key Patterns
• Delegation (Datasource)
• Alleviates subclassing
“I’m a table view. You need to give me a cell object to
display at row 5. I don’t really care what’s in it.”

121. Delegation
Delegate

122. Delegation
Delegate
“How many sections?”

123. Delegation
Delegate
“How many sections?”
“1”

124. Delegation
Delegate
“How many sections?”
“1”
“How many rows?”

125. Delegation
Delegate
“How many sections?”
“1”
“How many rows?”
“2”

126. Delegation
Delegate

127. Delegation
Delegate
“I need a cell for row 0”

128. Delegation
Delegate
“I need a cell for row 0”

129. Delegation
Delegate
“I need a cell for row 0”
“Someone tapped row 0”

130. UITableView
• Interface declares the datasource and
delegate protocols:

131. UITableView
• Interface declares the datasource and
delegate protocols:
@interface FirstViewController : UIViewController
<UITableViewDelegate, UITableViewDataSource>

132. UITableview
• Implements the required methods:

133. UITableview
• Implements the required methods:
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
- (NSInteger)tableView:(UITableView *)tableView
numberOfRowsInSection:(NSInteger)section
- (UITableViewCell *)tableView:(UITableView *)tableView
cellForRowAtIndexPath:(NSIndexPath *)indexPath
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:
(NSIndexPath *)indexPath

134. iOS 5

135. iOS 5
• Thousands of new APIs
• Newly available frameworks
• Game Center
• Automatic Reference Counting
• Storyboards
• iCloud
• It’s really really really big

136. Things we’ll cover:

137. Things we’ll cover:
• Automatic Reference Counting

138. Things we’ll cover:
• Automatic Reference Counting
• Twitter framework

139. Things we’ll cover:
• Automatic Reference Counting
• Twitter framework
• UIAppearance customization

140. Things we’ll cover:
• Automatic Reference Counting
• Twitter framework
• UIAppearance customization
• CoreImage Filters

141. Lobstagram

142. A Brief Tour

143. A Brief Tour
• A Table View of images already
taken

144. A Brief Tour
• A Table View of images already
taken
• Camera button chooses a photo
(or takes a photo)

145. A Brief Tour
• A Table View of images already
taken
• Camera button chooses a photo
(or takes a photo)
• Next view applies the photo title
and saves to CoreData

146. A Brief Tour
• A Table View of images already
taken
• Camera button chooses a photo
(or takes a photo)
• Next view applies the photo title
and saves to CoreData
• Table refreshes.

147. A Brief Tour
• A Table View of images already
taken
• Camera button chooses a photo
(or takes a photo)
• Next view applies the photo title
and saves to CoreData
• Table refreshes.
• Not worth $1 Billion

148. A Brief Tour

149. A Brief Tour
• UITableView as described earlier.

150. A Brief Tour
• UITableView as described earlier.
• UIImagePickerViewController is an
easy to use built in control.

151. A Brief Tour
• UITableView as described earlier.
• UIImagePickerViewController is an
easy to use built in control.
• CoreData is an ORM on steroids
for working with persistent
storage.

152. A Brief Tour
• UITableView as described earlier.
• UIImagePickerViewController is an
easy to use built in control.
• CoreData is an ORM on steroids
for working with persistent
storage.
• All written in ARC code.

153. The Dark Ages

154. The Dark Ages
• Manual Memory Management

155. The Dark Ages
• Manual Memory Management
• No garbage collection as in C#, Java, Ruby,
PHP, Python

156. The Dark Ages
• Manual Memory Management
• No garbage collection as in C#, Java, Ruby,
PHP, Python
• Reference counting system implemented on
NSObject.

157. The Dark Ages
• Manual Memory Management
• No garbage collection as in C#, Java, Ruby,
PHP, Python
• Reference counting system implemented on
NSObject.
• alloc . . . init

158. The Dark Ages
• Manual Memory Management
• No garbage collection as in C#, Java, Ruby,
PHP, Python
• Reference counting system implemented on
NSObject.
• alloc . . . init
• retain

159. The Dark Ages
• Manual Memory Management
• No garbage collection as in C#, Java, Ruby,
PHP, Python
• Reference counting system implemented on
NSObject.
• alloc . . . init
• retain
• release

160. The Dark Ages
• Manual Memory Management
• No garbage collection as in C#, Java, Ruby,
PHP, Python
• Reference counting system implemented on
NSObject.
• alloc . . . init
• retain
• release
• autorelease

161. The Dark Ages
• Manual Memory Management
• No garbage collection as in C#, Java, Ruby,
PHP, Python
• Reference counting system implemented on
NSObject.
• alloc . . . init
• retain
• release
• autorelease
• dealloc

162. Manual Memory
Management
• Classes
#import "MyClass.h"
@implementation MyClass
@synthesize aChildObject;
- (id)init
{
self = [super init];
if (self)
{
someItems = [[NSArray alloc] init];
}
return self;
}

163. Manual Memory
Management
• Continued . . .
- (void)dealloc
{
[aChildObject release];
[someItems release];
[super dealloc];
}
- (void)logMe
{
NSLog(@"MyClass");
}
+ (NSString *)className
{
return NSStringFromClass([self class]);
}
@end

164. No Longer

165. To The Code!

166. ARC Decorators

167. ARC Decorators
• __strong - owning reference (default)

168. ARC Decorators
• __strong - owning reference (default)
• __weak - non-owning reference

169. ARC Decorators
• __strong - owning reference (default)
• __weak - non-owning reference
• __unsafe_unretained - manual management

170. ARC Decorators
• __strong - owning reference (default)
• __weak - non-owning reference
• __unsafe_unretained - manual management
• __autoreleasing - used in out parameters

171. ARC Decorators
• __strong - owning reference (default)
• __weak - non-owning reference
• __unsafe_unretained - manual management
• __autoreleasing - used in out parameters
• No dealloc

172. Using __weak
• Use __weak to refer to an object that
you’re confident will be retained elsewhere.

173. Using __weak
• Use __weak to refer to an object that
you’re confident will be retained elsewhere.
NSArray *array = [NSArray arrayWithObjects:@"foo", @"bar",
@"baz", nil];
// The array is owning all the objects in it, so we don't
// need a strong reference here (but there's nothing wrong
with it)
NSString * __weak first = [array objectAtIndex:0];

174. __unsafe_unretained

175. __unsafe_unretained
• Used for backwards compatibility with iOS
4.

176. __unsafe_unretained
• Used for backwards compatibility with iOS
4.
• Pointer is NOT nil’d out after deallocation.

177. __unsafe_unretained
• Used for backwards compatibility with iOS
4.
• Pointer is NOT nil’d out after deallocation.
// nil initialization is automatic
NSNumber * __unsafe_unretained n = nil;
if (YES)
{
n = [[NSNumber alloc] initWithInt:25];
NSLog(@"%@", n);
}
// n loses scope
NSLog(@"%@", n); // CRASH! (probably)

178. __unsafe_unretained
• Used for backwards compatibility with iOS
4.
• Pointer is NOT nil’d out after deallocation.
// nil initialization is automatic
NSNumber * __unsafe_unretained n = nil;
if (YES)
{
n = [[NSNumber alloc] initWithInt:25];
NSLog(@"%@", n);
}
// n loses scope
n = nil;
NSLog(@"%@", n); // a-ok

179. __autoreleasing
• Used with out parameters
NSError * __autoreleasing error = nil;
if (![managedObjectContext save:&error])
{
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error"
message:@"The photo could not be saved"
delegate:nil
cancelButtonTitle:@"Ok"
otherButtonTitles:nil];
[alert show];
}
else
{
[delegate photoSettingsViewController:self didSaveNewPhoto:photo];
}
• (Note, the compiler will rewrite this if you
use a strong reference)

180. So what?

181. So what?
• ARC drastically reduces up front development
time.

182. So what?
• ARC drastically reduces up front development
time.
• ARC drastically reduces debugging time.

183. So what?
• ARC drastically reduces up front development
time.
• ARC drastically reduces debugging time.
• ARC is not perfect:

184. So what?
• ARC drastically reduces up front development
time.
• ARC drastically reduces debugging time.
• ARC is not perfect:
• Still possible to have retain cycle

185. So what?
• ARC drastically reduces up front development
time.
• ARC drastically reduces debugging time.
• ARC is not perfect:
• Still possible to have retain cycle
• Still need to understand pointer scope

186. So what?
• ARC drastically reduces up front development
time.
• ARC drastically reduces debugging time.
• ARC is not perfect:
• Still possible to have retain cycle
• Still need to understand pointer scope
• Doesn’t work on CF objects

187. So what?
• ARC drastically reduces up front development
time.
• ARC drastically reduces debugging time.
• ARC is not perfect:
• Still possible to have retain cycle
• Still need to understand pointer scope
• Doesn’t work on CF objects
• The compiler is smarter than you.

188. Twitter Integration
(Couldn’t be easier)

189. Twitter.framework

190. Twitter.framework
• TWTweetComposeViewController

191. Twitter.framework
• TWTweetComposeViewController
• Super easy view for composing a tweet

192. Twitter.framework
• TWTweetComposeViewController
• Super easy view for composing a tweet
• TWRequest

193. Twitter.framework
• TWTweetComposeViewController
• Super easy view for composing a tweet
• TWRequest
• Encapsulates the handling of HTTP
requests to the Twitter server.

194. Twitter.framework
• TWTweetComposeViewController
• Super easy view for composing a tweet
• TWRequest
• Encapsulates the handling of HTTP
requests to the Twitter server.
• Requires the user to have set up Twitter in
the device’s settings.

195. Tweet Composer
• Appears looking great
automatically.
• Can add links and images
• Literally zero
configuration.

196. To The Code!

197. Customizing
Appearance

198. Not a billion dollar app

199. The Dark Ages

200. The Dark Ages
• UI Customization was labor intensive

201. The Dark Ages
• UI Customization was labor intensive
• Every instance of a widget had to be
customized individually.

202. The Dark Ages
• UI Customization was labor intensive
• Every instance of a widget had to be
customized individually.
• Subclassing

203. The Dark Ages
• UI Customization was labor intensive
• Every instance of a widget had to be
customized individually.
• Subclassing
• Helper methods

204. The Dark Ages
• UI Customization was labor intensive
• Every instance of a widget had to be
customized individually.
• Subclassing
• Helper methods
• Overriding drawRect or haphazardly
adding subviews.

205. UIAppearance
• Certain UI Widgets expose an “appearance
proxy” which can be customized once and
the look persists everywhere.
[[UINavigationBar appearance] setTitleTextAttributes:navBarTextProperties];
[[UILabel appearanceWhenContainedIn:[UIButton class], nil] setTextColor:
[UIColor whiteColor]];
• Elements can also be customized
individually via the same methods.

206. What it’s not . . .
• A Cascading Style Sheet
• Outermost rule breaks a tie-
breaker
• No way to specify things by Id
• Unexpected consequences . . .

207. To The Code!

208. Much Better

209. Much Better

210. CoreImage

211. CoreImage

212. CoreImage
• A mature Mac-OS framework brought to
iOS.

213. CoreImage
• A mature Mac-OS framework brought to
iOS.
• Built in inclusion of filters for use

214. CoreImage
• A mature Mac-OS framework brought to
iOS.
• Built in inclusion of filters for use
• Plays nice with UIImage and CGImageRef

215. CoreImage Bits

216. CoreImage Bits
• CIImage - a recipe for creating an image.

217. CoreImage Bits
• CIImage - a recipe for creating an image.
• CIFilter - an ingredient in the recipe.

218. CoreImage Bits
• CIImage - a recipe for creating an image.
• CIFilter - an ingredient in the recipe.
• CIContext - the mixing bowl

219. CoreImage Workflow

220. CoreImage Workflow
• Create a CIContext

221. CoreImage Workflow
• Create a CIContext
• Grab an input image

222. CoreImage Workflow
• Create a CIContext
• Grab an input image
• Declare and configure a filter

223. CoreImage Workflow
• Create a CIContext
• Grab an input image
• Declare and configure a filter
• Get the output image from the filter

224. CoreImage Workflow
• Create a CIContext
• Grab an input image
• Declare and configure a filter
• Get the output image from the filter
• Billion dollar profit

225. Some caveats
• Documentation is scant
• The core image filter list applies to
MacOS only.
• To get the full list available on the iPhone:
NSLog(@"%@", [CIFilter filterNamesInCategory:kCICategoryBuiltIn]);
• There are filters in the device that aren’t
documented.

226. To The Code!

227. iOS 5 Development
• Web:
pzearfoss@gmail.com
http://zearfoss.wordpress.com
@pzearfoss
http://www.github.com/pzearfoss

229. https://github.com/pzearfoss/Lobstagram