iOS App Development

Day #1 : Fundamentals of Objective C

By Madusha Perera

iOS and the technology

iOS - Mobile OS by Apple Inc (2007)

History

Steve Jobs worked in Apple

Left Apple and created Next

NeXTSTEP OS

After coming back to Apple initiated iOS

Brad Cox : ObjC

Scott Forstall: iOS lead

Steve Jobs

Chris Lattner : Swift

Layers of iOS

iPhone / iPad Hardware

UIKit.framework/M

apKit.famework/ ...

ImageIO.framewor

k/CoreVideo.fame

work/ ...

CoreData.framewo

rk/CFNetwork.fam

ework/ ...

Security.framewor

k/LibSystem ...

M

O

B

I

L

E

A

P

P

Objective C - Data types

● int/double/float … (C primitives)

● NSInteger/NSUInteger (OC primitives)

● NSNumber

● NSString

● NSArray …

**NSLog() format specifiers … i,d,u,@

Pointers in ObjC

NSString *spell1 = @“abracadabra”

NSString *spell2 = spell1;

abracadabraspell1

spell2

Properties in ObjC

A better way to define iVars.

@property(nonatomic,weak) NSString *name;

This automatically generates the following

_name

setName

getname (naming convention in ObC)

ARC

Property Attributes

strong,weak,atmoic,nonatomic, … etc

Strong:

The Obj will remain till Owner Obj lives in heap.

defaults are

in red

+1

Owner Obj Obj

weak :

The Obj can be destroyed independently. If that

happens the reference value automatically will

become nil.

Owner Obj Obj

nil

Low memory

warning !

nonatomic/atomic:

Time

Thread #1

Thread #2

Obj

setName

getName

nonatomic is faster

Methods are self documenting

Declaration-(void) driveForDistance:(double)theDistance atSpeed:(double)speed;

+ for class methods

- for instance methods

Calling methods

[myRemoteCar driveForDistance:20 atSpeed:5];

Classes and Objects

A Class defines what an object

will look like when its created.

(define the states and behaviors.)

Objects are self contained modules that can be

easily used, re-used as building blocks for a

software application.

Interfaces and Implementation

classes (.h and .m files)

An ObjC class is defined in terms of an

interface and an implementation.

class

.h

.m

API exposed to other classes

Actual implementation of class

Interface (.h file)

@Interface NewClassname:ParentClass

<Protocol1>, <Protocol2> {

// private member variables}

//properties//public methods (instance or class methods)

@end

Implementation (.m file)

@implementation NewClassName

//method implementations@end

Protocols

Source:http://rypress.com/tutorials/objective-c/protocols

Protocols cont.

@protocol ProtocolName <NSObject>

@required//required method stubs

@optional//optional method stubs

@end

Protocol cont.

// StreetLegal.h

#import <Foundation/Foundation.h>

@protocol StreetLegal <NSObject>

- (void)signalStop;

- (void)signalLeftTurn;

- (void)signalRightTurn;

@end

Source:http://rypress.com/tutorials/objective-c/protocols

Protocol cont.

// Bicycle.h

#import <Foundation/Foundation.h>

#import "StreetLegal.h"

@interface Bicycle : NSObject <StreetLegal>

- (void)startPedaling;

@end

// Bicycle.m

#import "Bicycle.h"

@implementation Bicycle

- (void)signalStop {

NSLog(@"Bending left arm downwards");

}

- (void)signalLeftTurn {

NSLog(@"Extending left arm outwards");

}

- (void)signalRightTurn {

NSLog(@"Bending left arm upwards");

}

- (void)startPedaling {

NSLog(@"Here we go!");

}

@end

Source:http://rypress.com/tutorials/objective-c/protocols

Design Patterns : Delegate

Design Pattern : A general reusable solution to

a commonly occurring problem.

Delegate Pattern

Delegate

Delegator

Where it all starts : main()

Hands control to the UIKit framework.

iOS App Development

Day #2 : Building an App with UI

Where it all starts : main()

Hands control to the UIKit framework.

Delegate Pattern in use

Architectural Pattern : MVC

Controller

Accept user input and react orchestrate

View

ModelBusiness Logic + Data

Core functionality and data

Display information to the user

States

Launched or

terminated

Running but not

receiving events

(phone call/sms)

Running in

background if

permits

Source:https://developer.apple.com

Source:https://developer.apple.com

IBOutlets and IBAction

IB : Interface Builder

Outlet and IBAction are just flags to tell the

xcode this is to do with the UI

Connecting the things

Lets create a small app ...