Fundamentals for programmers new to iOS development with Objective-C

1. INTRODUCTION
to iOS Programming

2. ME
• Travel & outdoor sports
• Chemical engineering
• Freezer engineering
• Software consultant, technology businesses
• Optometry & Real Estate

3. ME
• http://calvinx.com
• Twitter @calvinchengx
• FB http://facebook.com/calvin.cheng.lc
• Github http://github.com/calvinchengx

4. YOU?

5. WHY?
• Why do we learn programming?
• Why do you want to learn programming?
• What problems do you want to solve?
• Who can we help?

6. OVERVIEW
• Lesson 1: Introductions
• Lesson 2: iOS specifics
• Lesson 3: Data Model
• Lesson 4: Logic (Controller) & Interface

7. LESSON 1:
INTRODUCTIONS
• Hour 1 - Demo and Set-up
• Hour 2 - Objective-C Primer
• Hour 3 - MVC Architecture

8. DEMO

9. APPLE DEVELOPER

10. PREREQUISITES
• Do you know an existing programming
language or scripting language?
• Control logic, data and interfaces - what do
you want the user to see and/or do?
• Objective-Oriented Programming?

11. COMPARISONS

12. OBJECT-ORIENTED
PROGRAMMING
• Class
• Objects
• Functions
• Methods

13. KNOW A PROGRAMMING
LANGUAGE?
• C
• Java?
• Javascript?
• Python?
• Ruby?

14. C-STYLE LANGUAGES
• C
• C++
• Objective-C as a superset of C
• PHP
• C#
• Java
• Perl

15. OBJECTIVE-C SYNTAX
• @ is used to identify Objective-C
• Special keywords, e.g. protocol, property,
interface, implementation, NSObject,
NSInteger, NSNumber etc
• Tokens, e.g. @, (, ; etc

16. XCODE: CREATE PROJECT

17. XCODE: CREATE PROJECT

18. OBJECTIVE-C PRIMER

19. • Basic Syntax
• Variables and Data Types
• Working with Objects
• Classes and Objects
• Collections
• Files
• Language Features
• Errors and Debugging

20. BASIC SYNTAX
• Objective-C is a superset of C programming
language
• i.e. it understands all C syntax
• AND it introduces new syntax of its own on
top of C

21. BASIC SYNTAX

22. BASIC SYNTAX

23. BASIC SYNTAX
Code is grouped into “pairs” of:
• Header file
• Implementation file

24. BASIC SYNTAX

25. BASIC SYNTAX

26. BASIC SYNTAX

27. VARIABLES & DATA TYPE
myemail@domain.com
#ffffff
37
2008-08-08

28. VARIABLES & DATA TYPE
myemail@domain.com
#ffffff
37
2008-08-08
email:
color:
age:
date of event:

29. VARIABLES & DATA TYPE
Javascript
var a = “wonderful”;
a = 123;
a = 1.289;
a = false;

30. VARIABLES & DATA TYPE
Objective-C
type variable value
int homeworkScore = 87;

31. VARIABLE & DATA TYPE
Naming convention: camel case
firstName
score
playerKarma
my8Number NOT RECOMMENDED
int_score NOT RECOMMENDED

32. VARIABLES & DATA TYPE
Primitive Data Types
int
float
double
char
BOOL Objective-C

33. VARIABLES & DATA TYPE
Composite Data Types
int day = 28;
int month = 11;
int year = 2011;
int secondsSince1970 = 1294909373;
char c1 = ‘h’;
char c2 = ‘e’;
char c3 = ‘l’;
char c4 = ‘l’;
char c5 = ‘o’;

34. VARIABLES & DATA TYPE
Complex Types: iOS SDK (CocoaTouch
Framework)
NSString *myString = @“Hello”;
NSDate *today = [NSDate date];

35. WORKING WITH OBJECTS
Procedural Program (Example C program)

36. WORKING WITH OBJECTS
Object Oriented Programs (Objective-C)
data
logic
data
logic
data
logic

37. WORKING WITH OBJECTS
class object

38. CLASS = OBJECT
BLUEPRINT

39. CLASS = OBJECT
BLUEPRINT
NSDate *today = [NSDate date];
ref -
https://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Cl
asses/NSDate_Class/Reference/Reference.html

40. CLASS = OBJECT
BLUEPRINT
NSDate *today = [NSDate date];
ref -
https://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Cl
asses/NSDate_Class/Reference/Reference.html
What’s this?

41. CLASS = OBJECT
BLUEPRINT
• Pointers!
• All objects are accessed using Pointers
• * represents a pointer and a primitive value

42. USING OBJECTS

43. CLASS = OBJECT
BLUEPRINT
NSDate *today = [NSDate date];
ref -
https://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Cl
asses/NSDate_Class/Reference/Reference.html
What’s this?

44. METHODS
NSDate *today = [NSDate date];
ref -
https://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Cl
asses/NSDate_Class/Reference/Reference.html
MethodClassType Pointer
denotes that this variable is a Pointer

45. METHODS
• Class Methods
• Instance Methods (also known as Object
Methods)

46. METHODS
NSDate *today = [NSDate date]
NSTimeInterval timeInterval = 123;
NSDate *dateFromInterval = [NSDate
dateWithTimeInterval:timeInterval
sinceDate:today]
Class Method

47. METHODS
NSComparsionResult result = [today
compare:dateFromInterval]
Instance Method
a.k.a. Object Method
NSDate object from previous slide
NSDate object from previous slide

48. COLLECTIONS
• A group of data or objects
• Various languages refer to them as “arrays”
or “lists” or “dictionaries” or “linked lists”
(each with slightly different underlying
meaning)

49. COLLECTIONS

50. FILES

51. FILES
• All programming languages provide a way to
write to your computer’s/operating system’s
filesystem
• If we cannot put things into a file, the data
that we are working with will not be available
when our computer is switched off since it’s
only in the memory

52. FILES

53. LANGUAGE FEATURES
• Inheritance (e.g. NSObject > NSResponder > NSView >
NSControl > NSButton)
• Categories: extending a class with new methods without
sub-classing

54. LANGUAGE FEATURES
• Class Extensions: extending a class with new
properties without sub-classing (only “.h”
created, no implementation file :-))

55. LANGUAGE FEATURES
• Categories versus Class Extensions

56. LANGUAGE FEATURES
• Protocols: a list of methods you want a object to
perform
• required methods
• optional methods
• ANY object can perform those methods
• Think of it as a set/group of methods (“functions”)

57. LANGUAGE FEATURES
• Dynamic Typing with id
• id is a generic object pointer

58. ERRORS & DEBUGGING
• Issue navigator
• Pick the first error (don’t start at the bottom)
• Common errors:
• Missing pointer symbol
• Missing semi-colons or braces (parsing error)
• Undeclared identifier (didn’t import a header?)
• Learning to use breakpoints

59. MVC ARCHITECTURE
• What is MVC?
• Using the iOS Simulator in Xcode
• Exercise Files
• Features of our Note Taking App

60. WHAT IS MVC?
• Model
• View
• Controller

61. WHAT IS MVC?
Model
• Representation of your class (“blueprint”, .h, .m)
• Set properties and behaviour of your class
• Set properties and behaviour of your class’ objects
• Handles data storage in memory
• Handles data storage on disk
• Handles data storage to the “cloud”/backend

62. WHAT IS MVC?
View
• The interface for the user of your app - “Scene”, “Storyboard”
• Listens to user interactions - tap, swipe, other events (shaking
your phone)
• Shows the user responses and ask for user responses
• Aesthetic purpose as well as User function purpose
• Usually tied to the logic (i.e. “controller”)

63. WHAT IS MVC?
Controller
• “ViewController” (.h, .m)
• Your app should be organised with multiple ViewControllers with
different purposes
• Calls out classes, class methods, objects, object methods from
your models, changes data according to user interactions and
accepts or pushes data to the view
• Using linked to scenes and UI (User Interface) object(s) on a
scene

64. WHY MVC?
• Organised, modular (cleanly separated code
for easy debugging)
• A convention for teamwork so others can
easily get the “big picture” of the components
that make your app work

65. IOS SIMULATOR

66. EXERCISE FILES
• Github url

67. FEATURES OF OUR NOTE
TAKING APP
• Show list of notes
• Create a note and be able to persist the note
(“save”)
• Edit a note
• Delete a note

68. WHAT’S NEXT?
• Lesson 1: Introductions
• Lesson 2: iOS specifics
• Lesson 3: Data Model
• Lesson 4: Logic (Controller) & Interface