iOS Developer Overview - DevWeek 2014

iOS Application Development
iOS Developer Overview
Paul Ardeleanu

Assumptions…
You are:

‣ a developer of sorts…

‣ have no or little exposure to iOS

‣ want to learn enough to become ‘dangerous’

The plan
‣ Why iOS?

‣ Tools

‣ Storyboarding

‣ Objective-C

‣ Design patterns

‣ Debug & Testing

‣ Ad-Hoc distribution

‣ Publishing in the app store

Why iOS?

Once upon a time…

… there were phones
http://www.ﬂickr.com/photos/adrianblack/371301544/

Before & after
https://twitter.com/JoshHelﬀerich

Global Phone Market
Units shipped / quarter
© Asymco - used with permission

Smartphone shipments

Developer tools

Building great apps

Building great apps
‣ Constraints

‣ small size

‣ limited hardware

‣ one screen at a time

‣ one application at a time *

‣ touch input
‣ Interaction

‣ gestures

‣ shake

‣ orientation

‣ audio switch, volume buttons

‣ home & power buttons

List of
features
too many
features?
Filter
Yes
Application
Deﬁnition
Statement
App
features
User journeys
Wirefames
Prototype

Application Deﬁnition Statement
“A concise, concrete declaration of the app’s
main purpose and its intended audience.”
https://developer.apple.com/library/ios/documentation/
UserExperience/Conceptual/MobileHIG/

Solve real problems
"An app must solve a user's problem
clearly and elegantly."

Eric Hope, User Experience Evangelist, Apple

Delivery channels
‣ web app [dedicated]

‣ native app

‣ “hybrid” solutions

Storyboarding

What is Storyboarding
‣ Design the “screens” that compose your app => scenes

‣ Visually deﬁne the navigation between the scenes => segues

‣ Introduced in: iOS 5 & Xcode 4.2

Specialised View Controllers
‣ UITableViewController

‣ UINavigationController

‣ UITabBarController

‣ UICollectionView

Objective-C

What is Objective C
‣ Thin layer on top of C; strict superset of C

‣ Object-oriented programming language

‣ Inspired by SmallTalk

‣ Developed by Stepstone / NeXT Software / Apple

‣ The development language for Mac OSX & iOS devices

Object-Oriented Programming
a programming paradigm that uses "objects"
!
myCar
• Number of wheels

• Number of seats

• Colour

• Engine size

• Top speed
• Drive

• Brake

• Turn Left

• Beep

• Fill with petrol
MethodsProperties
Data + Behaviour

Vehicle class
Interface .h Implementation .m
Vehicle.h Vehicle.m
@interface
Vehicle
{

int
wheels;

int
seats;

}

!
-‐
(void)drive;

-‐
(void)setWheels:(int)n;

!
@end
#import
"Vehicle.h"

!
@implementation
Vehicle

!
-‐
(void)setWheels:(int)n
{

wheels
=
n;

}

!
-‐
(void)drive
{

…

}

!
@end

Methods syntax
-‐
return type name argument type
argument name
type

Multiple arguments
-‐
(BOOL)application:(UIApplication
*)application

didFinishLaunchingWithOptions:(NSDictionary
*)launchOptions
application:didFinishLaunchingWithOptions:
The name of the method is:

Multiple arguments
+ (void)animateWithDuration:(NSTimeInterval)duration
delay:(NSTimeInterval)delay
options:(UIViewAnimationOptions)options
animations:(void (^)(void))animations
completion:(void (^)(BOOL finished))completion;
animations:(void (^)(void))animations;

Multiple arguments
[UIView animateWithDuration:1.0
delay:0.3
options:UIViewAnimationOptionCurveEaseIn
animations:^{
// animations
} completion:^(BOOL finished) {
// completion block
}
];
delay:(NSTimeInterval)delay
options:(UIViewAnimationOptions)options
animations:(void (^)(void))animations
completion:(void (^)(BOOL finished))completion;

Properties
@implementation
Vehicle

!
-‐
(int)wheels
{

return
wheels;

}

!
-‐
(void)setWheels:(int)n
{

wheels
=
n;

}

!
@end
@interface
Vehicle
:
NSObject
{

int
wheels;

}

!
-‐
(int)wheels;

-‐

!
@end
@implementation
Vehicle

!
!
!
@end
@interface
Vehicle
:
NSObject
{

!
}

!
@property
int
noWheels;

!
@end

int
numberWheels;

@synthesize
numberWheels;

Properties & dot notation
Vehicle
*myCar
=
[Vehicle
new];

!
myCar.wheels
=
5;

!
myCar.wheels

What is a method?
typedef
struct
objc_selector
*SEL;
!
Vehicle
*myCar
=
[Vehicle
new];

!
[myCar
drive];
objc_msgSend(myCar,
@selector(drive))

Sending a message
-‐
(void)setWheels:
(int)n;
[myCar
setWheels:4];
objc_msgSend(myCar,
@selector(setWheels:),
4);

Sending a message
!
Vehicle
*myCar
=
nil;

!
[myCar
drive];

myCar
=
...;

if
([myCar
respondsToSelector:@selector(drive)])
{

[myCar
drive];

}

Initialisers
Vehicle *myCar = [Vehicle new];
-‐
(id)initWithWheels:(int)wheels
{

self
=
[super
init];

if
(nil
!=
self)
{

//
Custom
initialization

self.wheels
=
wheels;

}

return
self;

}
Vehicle *myCar = [[Vehicle alloc] initWithWheels:4];
Vehicle *myCar = [[Vehicle alloc] init];

InitialisersMultiple
@interface
Vehicle
:
NSObject

!
@property
int
wheels;

@property
int
seats;

!
-‐
andSeats:(int)seats;

-‐
(id)initWithWheels:(int)wheels;

-‐
(id)initWithSeats:(int)seats;

!
@end

InitialisersMultiple
-‐
(id)init
{

return
[self
initWithWheels:DefaultNumberWheels
andSeats:DefaultNumberSeats];

}

#define
DefaultNumberWheels
4

#define
DefaultNumberSeats
5
-‐
andSeats:(int)seats{

self
=
[super
init];

if
(nil
!=
self)
{

self.wheels
=
wheels;

self.seats
=
seats;

}

return
self;

}
-‐
{

return
[self
initWithWheels:wheels
andSeats:

];

}
-‐
(id)initWithNumberSeats:(int)seats
{

return
[self
initWithWheels:DefaultNumberWheels
andSeats:seats];

}
DefaultNumberSeats

Inheritance
@interface
Truck
:
Vehicle

!
!
!
!
!
!
!
!
!
!
!
@end

@interface
Vehicle
:
NSObject

!
@property
int
wheels;

@property
int
seats;

!
-‐
(void)drive;

!
@end -‐
(void)checkLoad;

-‐
(void)loadWithWeight:(int)weight;

-‐
(void)unload;

{

int
maxWeight;

}
@property
int
currentWeight;

Inheritance
NSObject
NSPredicateNSArray
NSComparisonPredicate
NSMutableArray
UIResponder
UIView
UIWindow UIControl
UIButton
UIGestureRecognizer
UIApplicationNSNumber
NSValue

instance
class
isa
superclass
superclass
metaclass
isa
metaclass
isa
superclass
NSObject
superclass
superclass
nil
metaclass
isa
superclass
superclass

Polymorphism & Dynamic typing
Vehicle
Truck

!
- (void)drive
Car

!
- (void)drive
id
aVehicle;

!
...

!
[aVehicle
drive];

id
‣ the generic object type

‣ can be used for object of any type

‣ the object class is determined at runtime (dynamic typing)
Vehicle
*aCar;
Static typing
id
aCar;
Dynamic typing

Introspection
NSObject
- (BOOL)isKindOfClass:(Class)aClass;
- (BOOL)isMemberOfClass:(Class)aClass;
- (Class)superclass;
- (Class)class;
- (BOOL)respondsToSelector:(SEL)aSelector;

Protocols
-‐
(void)load;

-‐
(void)unload;

-‐
(float)getWeight;
@interface
Truck
:
Vehicle
@end

Protocols
-‐
(void)load;

-‐
(void)unload;

-‐
(float)getWeight;
@implementation
Truck

!
!
!
!
!
!
!
!
!
!
!
!
!
@end
-‐
(void)load
{

...

}

-‐
(void)unload
{

...

}

-‐
(float)getWeight
{

...

}

@interface
Truck
:
Vehicle
@end

Protocols
-‐
(void)load;

-‐
(void)unload;

-‐
(float)getWeight;
@interface
Truck
:
Vehicle
@end
@protocol
VehicleLoading
@end
<VehicleLoading>

Protocols
-‐
(void)load;

-‐
(void)unload;

-‐
(float)getWeight;
@interface
Truck
:
Vehicle
@end
@protocol
VehicleLoading
@end
<VehicleLoading>
@implementation
Truck

!
!
!
!
!
!
!
!
!
!
!
!
!
@end
-‐
(void)load
{

...

}

-‐
(void)unload
{

...

}

-‐
(float)getWeight
{

...

}

Category
@interface
Vehicle
:
NSObject

!
...

!
-‐
(void)drive;

-‐
(void)brake;

!
@end
!
Vehicle
*myCar
=
[Vehicle
new];

[myCar
steerLeft];

Category
@interface NSString : NSObject
!
!
!
!
!
!
@end

@interface NSString : NSObject
!
!
!
!
!
!
@end
Category
- (NSUInteger)wordCount;

Category
#import
"NSString.h"

!
@interface
NSString
(H24Utils)

!
-‐
(NSUInteger)wordCount;

!
@end
NSString+H24Utils.h NSString+H24Utils.m

Category
#import
"NSString.h"

!
@interface
NSString
(H24Utils)

!
-‐
(NSUInteger)wordCount;

!
@end
NSString+H24Utils.h NSString+H24Utils.m
#import
"NSString+H24Utils.h"

!
@implementation
NSString
(H24Utils)

!
-‐
(NSUInteger)wordCount
{

…

}

!
@end

Naming conventions
Classes
Objects
camelCase with capitalised ﬁrst letter (a.k.a. Pascal case)
Preﬁxes
HelloWorldViewController

camelCase
viewController,
myCar

NSArray,
UIView

BOOL data type
typedef
signed
char

BOOL;

!
#define
YES
(BOOL)1

#define
NO

(BOOL)0

Blocks
void
(^sayHello)(NSString
*)
=
^(NSString
*name)
{

NSLog(@“Hello
%@",
name);

};
NSString
*sayHello
=
@"Hello
World";

Blocks
void
*);

!
sayHello
=
^(NSString
*name)
{

NSLog(@"Hello
%@",
name);

};
void
*)
=
^(NSString
*name)
{

NSLog(@“Hello
%@",
name);

};

Blocks
@interface
Person
:
NSObject

!
@property
NSString
*name;

!
-‐
(void)welcomeUserWithBlock:(void
(^)(NSString
*))theBlock;

!
@end
@implementation
Person

!
…

!
-‐
(void)welcomeUserWithBlock:(void
(^)(NSString
*))theBlock
{

theBlock(self.name);

}

!
@end

Blocks
void
*)
=
^(NSString
*name)
{

NSLog(@“Hello
%@",
name);

};
Person
*theUser
=
[[Person
alloc]
initWithName:@"Paul"];
[theUser
welcomeUserWithBlock:^(NSString
*name)
{

NSLog(@"Hello
%@",
name);

}];
[theUser
welcomeUserWithBlock:sayHello];

Blocks
Person
*theUser
=
[[Person
alloc]
[theUser
*name)
{

NSLog(@"Hello
%@",
name);

}];

Block scope
!
!
Person
*theUser
=
[[Person
alloc]

!
[theUser
*name)
{

NSLog(@"Hello
%@",
name);

}];

message
Module09_02[8635:303] Hello Paul
NSString
*message
=
@"Hello
%@";

Block scope
NSString
*message
=
@"Hello
%@";

!
!
!
!
!
!
Person
*theUser
=
[[Person
alloc]

!
[theUser
*name)
{

NSLog(@"Hello
%@",
name);

}];

message
...

!
if
(morning)
{

message
=
@"Good
morning
%@";

}
Module09_02[8693:303] Good morning Paul

Example
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Hello"
message:@"Are you sure?"
delegate:self
cancelButtonTitle:@"No"
otherButtonTitles:@"Yes", nil];
[alert show];
- (void)alertView:(UIAlertView *)alertView
clickedButtonAtIndex:(NSInteger)buttonIndex {
...
}

Example
@interface
UIAlertView
(H24Blocks)

!
!
+
(UIAlertView*)
alertViewWithTitle:(NSString*)
title

message:(NSString*)
message

cancelButtonTitle:(NSString*)
cancelButtonTitle

otherButtonTitles:(NSArray*)
otherButtons

onDismiss:(IndexBlock)
dismissed

onCancel:(EmptyBlock)
cancelled;

!
@end

Example
[UIAlertView
alertViewWithTitle:@"Hello"

message:@"Hello
World"

cancelButtonTitle:@"Cancel"

otherButtonTitles:@[@"OK"]

onDismiss:^(int
buttonIndex)
{

NSLog(@"Dismissed");

}
onCancel:^{

NSLog(@"Cancelled");

}];

Design Patterns

Design Patterns
‣ Accessors Pattern

‣ allows access to an object properties through simple methods

‣Anonymous Type Pattern

‣ send message to objects of an uncertain (at compilation) type

‣2-stage Object Creation Pattern

‣ alloc + init = new

‣ allow custom initialisers

‣Outlets, targets & actions

‣ conﬁguration of and interaction with UI elements

[M]VC
Model
View Controller
!View
Controller

Decorator pattern
‣ add bevaviour to an object

‣ without aﬀecting the behaviour of other objects from the same
class

Categories
‣ adds functionality to classes without the need to subclass

‣ group common methods and implement them across the
relevant framework

‣ informal protocols (unimplemented methods)

‣ anonymous category (private methods)

Delegation
‣ a delegate is an object that works together with its delegator to
solve a problem

‣ a delegate adds/changes the behaviour of the delegator (avoids
subclassing)

‣ loose coupling

‣ a delegate is usually referenced using the anonymous type
@interface MyAppDelegate : NSObject <UIApplicationDelegate>

Observer pattern
‣ enables communication between objects

‣ no coupling

‣ one object notiﬁes another object (registered as ‘listener’) when
a change occurs

Notifications
‣ an object registers as observer

‣ when a notification is sent to the Notification Center, it is
distributed to all listeners
[NSNotificationCenter
defaultCenter]

Notiﬁcations
[[NSNotificationCenter
defaultCenter]
addObserver:self

selector:@selector(soSomething)

name:@"H24CourseNotification"

object:nil];

defaultCenter]
postNotificationName:@"H24CourseNotification"

object:nil];

defaultCenter]
removeObserver:self];

Key-Value Observing
‣ KVC - Key Value Coding

‣ KVO - Key Value Observing

KVC
@interface
Vehicle
:
NSObject
@end

KVC
@interface
Vehicle
:
NSObject
@end
@property
NSString
*maker;

KVC
@interface
Vehicle
:
NSObject
@end
myCar.maker

[myCar
maker]
myCar.maker
=
@"Ford";

[myCar
setMaker:@"Ford"];
@property
NSString
*maker;

KVC
@interface
Vehicle
:
NSObject
@end
[myCar
valueForKey:@"maker"];

[myCar
setValue:@"Ford"
forKey:@"maker"];
myCar.maker

[myCar
maker]
myCar.maker
=
@"Ford";

[myCar
setMaker:@"Ford"];
@property
NSString
*maker;

KVC
@interface
Vehicle
:
NSObject
@end
@property
User
*owner;
myCar.maker

[myCar
maker]
myCar.maker
=
@"Ford";

[myCar
setMaker:@"Ford"];
@property
NSString
*maker;
[myCar

[myCar
setValue:@"Ford"
forKey:@"maker"];

KVC
@interface
Vehicle
:
NSObject
@end
@property
User
*owner;
[myCar
valueForKeyPath:@"owner.firstName"]

[myCar
setValue:@"John"
forKeyPath:@"owner.firstName"];

myCar.maker

[myCar
maker]
myCar.maker
=
@"Ford";

[myCar
setMaker:@"Ford"];
@property
NSString
*maker;
[myCar

[myCar
setValue:@"Ford"
forKey:@"maker"];

KVO
[aVehicle
addObserver:self

forKeyPath:@"owner"

options:NSKeyValueObservingOptionNew

context:nil];
options:(NSKeyValueObservingOptionNew
|
NSKeyValueObservingOptionOld)

KVO
- (void)observeValueForKeyPath:(NSString *)keyPath "
ofObject:(id)object "
change:(NSDictionary *)change "
context:(void *)context

KVO
[vehicle
removeObserver:self
forKeyPath:@"owner"];

Facade pattern
‣ simplified interface to a larger body of code

‣ subsystems accessed through a well defined entry point

‣ allows subsystems to change without affecting the overall
functionality

UIImage
+
(UIImage
*)imageWithContentsOfFile:(NSString
*)path
+
(UIImage
*)imageNamed:(NSString
*)name

Anatomy of an app
#import
<UIKit/UIKit.h>

!
#import
"AppDelegate.h"

!
int
main(int
argc,
char
*
argv[])

{

@autoreleasepool
{

return
UIApplicationMain(argc,
argv,
nil,

NSStringFromClass([AppDelegate
class]));

}

}
main.m

App states

Slide Hello24 Ltd. (c) 2014
App states
122
Active
Inactive
Running
Suspende
Running
Not running
Background

No background
123

App life cycle
124
Active
Inactive
Running
Suspended
iPhone OS 3 iOS 4
Running
Not running
Running
Not running
Background

AppDelegate callbacks
‣ application:willFinishLaunchingWithOptions:

‣ application:didFinishLaunchingWithOptions:

‣ applicationDidBecomeActive:

‣ applicationWillResignActive:

‣ applicationDidEnterBackground:

‣ applicationWillEnterForeground:

‣ applicationWillTerminate:
125

Foreground
Background
Not running
App life cycle
126
Active
Inactive
Running
Suspended

App life cycle - app start
127
ForegroundActive
Inactive
BackgroundRunning
Suspended
Not running
1

Foreground
Background
Not running
App life cycle
128
Active
Inactive
Running
Suspended
willFinishLaunchingWithOptions:
1

Foreground
Background
Not running
App life cycle
129
Active
Inactive
Running
Suspended
2
1

Foreground
Background
Not running
App life cycle
130
Active
Inactive
Running
Suspended
2
1
didFinishLaunchingWithOptions:

Foreground
Background
Not running
App life cycle
131
Active
Inactive
Running
Suspended
2
1
didFinishLaunchingWithOptions:
applicationDidBecomeActive:

Foreground
Background
Not running
App life cycle - inactive
132
Active
Inactive
Running
Suspended

Foreground
Background
Not running
App life cycle
133
Active
Inactive
Running
Suspended

Foreground
Background
Not running
App life cycle
134
Active
Inactive
Running
Suspended
applicationDidResignActive:

Foreground
Background
Not running
App life cycle
135
Active
Inactive
Running
Suspended

Foreground
Background
Not running
App life cycle
136
Active
Inactive
Running
Suspended

Foreground
Background
Not running
App life cycle - background
137
Active
Inactive
Running
Suspended

Foreground
Background
Not running
App life cycle
138
Active
Inactive
Running
Suspended
1

Foreground
Background
Not running
App life cycle
139
Active
Inactive
Running
Suspended
1

Foreground
Background
Not running
App life cycle
140
Active
Inactive
Running
Suspended
1
2

Foreground
Background
Not running
App life cycle
141
Active
Inactive
Running
Suspended
1
2
applicationDidEnterBackground:

Foreground
Background
Not running
App life cycle
142
Active
Inactive
Running
Suspended
1
2
7

Foreground
Background
Not running
App life cycle
143
Active
Inactive
Running
Suspended
1
2
7 8

Foreground
Background
Not running
App life cycle
144
Active
Inactive
Running
Suspended
1
2
7 8
9

Foreground
Background
Not running
App life cycle
145
Active
Inactive
Running
Suspended
1
2
7 8
9
applicationDidEnterForeground:

Foreground
Background
Not running
App life cycle
146
Active
Inactive
Running
Suspended
1
2
7 8
9
10

Foreground
Background
Not running
App life cycle
147
Active
Inactive
Running
Suspended
1
2
7 8
9
10

Foreground
Background
Not running
App life cycle - terminate
148
Active
Inactive
Running
Suspended

Foreground
Background
Not running
App life cycle
149
Active
Inactive
Running
Suspended

Foreground
Background
Not running
App life cycle
150
Active
Inactive
Running
Suspended

Foreground
Background
Not running
App life cycle
151
Active
Inactive
Running
Suspended
applicationWillTerminate:

Debug & Testing

Network Link Conditioner on device

Pony Debugger
[16:04:17] paul@Pro2x:project1 [502] $ ponyd serve --listen-interface=127.0.0.1
PonyGateway starting. Listening on 127.0.0.1:9000
[17:14:22] paul@Pro2x:MyPony [516] $ pod install
Setting up CocoaPods master repo
Setup completed (read-only access)
Analyzing dependencies
Downloading dependencies
Installing PonyDebugger (0.3.1)
Installing SocketRocket (0.3.1-beta2)
Generating Pods project
Integrating client project
!
[!] From now on use `MyPony.xcworkspace`.
[deprecated] I18n.enforce_available_locales will default to true in the future. If you really want to
skip validation of your locale you can set I18n.enforce_available_locales = false to avoid this
message.

Pony Debugger

PDDebugger
*debugger
=
[PDDebugger
defaultInstance];

[debugger
connectToURL:[NSURL
URLWithString:@"ws://127.0.0.1:9000/device"]];

[debugger
forwardAllNetworkTraffic];

[debugger
enableCoreDataDebugging];

[debugger
addManagedObjectContext:self.managedObjectContext
withName:@"MyPony"];

[debugger
enableViewHierarchyDebugging];

[debugger
enableRemoteLogging];

Ad-Hoc distribution

Publishing

Review
http://reviewtimes.shinydevelopment.com/

What is an app?

What is an app?
‣ A package that is installed on a device

‣ Runs in a sandboxed environment

‣ Has limited access to system resources

‣ The limits can change over time

‣ Can retrieve remote information (when connection available)

‣ Can run in background

Thank you!
@pardel

!
hello24.com

paul@hello24.com

iOS Developer Overview - DevWeek 2014

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iOS Developer Overview - DevWeek 2014