A primer on Objective-C and iPhone programming presented during December 2012 iOS Dev Scout Hackathon

1. OBJECTIVE-C AND YOU
First step on your Journey to writing iOS apps
Monday, January 14, 13

2. ABOUT
• Started Programming since 14 years old. iPhone development
for 2+ years
• Runs software development company Getting Real - Clients
include Prestige Magazine, Google Earth Hour etc..
• Does iOS Corporate Training - Clients include OCBC, Imerys,
Barclays bank, IDA etc..
• Decided to go into mobile development because
smartphones have changed and will continue to change the
world
Monday, January 14, 13

3. WHY LEARN APP
DEVELOPMENT?
• As of Jan 2013 - Apple has paid out of USD $7 billion to
developers
• Apple now has over 200 million iTunes accounts - the largest
credit card hub on the internet. Earning money online has
never been easier
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4. PREREQUISITES
• An Intel-based Mac
• Xcode IDE
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5. OBJECTIVE-C BASICS
And a random motorcycle.
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6. WHAT IS OBJECTIVE-C?
•A general purpose, high-level, object-oriented programming
language that is a wrapper over C programming language
• The main programming language used by Apple for iOS
programming
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7. WHY OBJECTIVE-C?
• Use Objective-C if you don’t want your app to suck. Seriously.
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8. OBJECT ORIENTATION
• Using objects as ‘data models’
•A way to think about programming
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9. VOCABULARY
• Class - The generic “type” of an object. e.g. Smartphones
• Instance - A specific object of a given class. e.g. iPhone 5
• Method - A function that an object performs. e.g. Make call,
send message, surf for cat pictures on 9GAG
• Variable - A quantity or value. e.g. Percentage of battery life,
number of messages in inbox.
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10. MORE VOCABULARY
• Class - Car
• Instance - BMW Z4
• Methods - Drive, convert
roof, attract women
• Variables - Amount of fuel,
speed (km/h)
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11. DATA TYPES
Name Explanation Example
void Nothing -
int Integer or number 1, 2, 3
float Decimal-point 3.14562
BOOL Yes or No YES, NO
NSString Sentence/ Word @”Hello World”
id Anything -
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12. DECLARING DATA TYPES
int cupsOfCoffee;
int amountOfWork
float productivityLevel;
cupsOfCoffee = 3;
productivityLevel = cupsOfCoffee * amountOfWork;
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13. DEFINING VARAIBLES
Class *objectName;
- NSString *mySentence;
What is the * ?
Not for C types like int, float, BOOL
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14. METHODS
•A function that an object can perform
• Can return a value, or not
• e.g. the BMW class will have a getPrice method
- (int)getPrice:(Car *)typeOfCar {
// Input code here
return carPrice;
}
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15. METHODS
• Use Parameters / Arguments to pass more information to
methods
• Example: squareNumber
- (int) squareMe: (int)x {
return x * x;
}
[self squareMe:20];
Monday, January 14, 13

16. METHODS
• Methods with more than one parameter/ argument
• Example: multiplyNumbers
- (int) multiplyNumbers: (int)x andSecondNumber: (int)y{
return x * y;
}
int numProduct = [self multiplyNumbers:10 andSecondNumber:50];
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17. METHODS
• Invoking Methods on Objects
[object method];
[object methodWithArgument:argument];
int variable = [object methodWithArgument:argument];
float batteryLifeLeft = [iPhone getBatteryLife];
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18. LOOPS AND CONDITIONS
Making your code smart
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19. LOOPS
• Execute a piece of code multiple times
• Automate repetitive tasks
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20. FOR LOOP
• Running a ‘for’ loop
for ( initialization ; test condition ; increment) {
// Code block
}
for ( int i = 0 ; i < 10 ; i++) {
NSLog(@”Hello fellow iOS devs!”);
}
• This will print “Hello fellow iOS devs!” to the console 10 times
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21. WHILE LOOP
• Running a ‘while’ loop
while (condition is true) {
// Execute code
}
BOOL isNetworkConnected = YES;
while (isNetworkConnected) {
[self downloadData];
}
• This will download data so long as the network is connected
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22. CONDITIONALS
• An important idea in programming is taking different actions
depending on different circumstances
• Conditional expressions are always either true or false
• e.g. Is there coffee available in the pantry? If yes, make some
coffee. If not, lament in despair (or just go out and buy some)
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23. IF-ELSE STATEMENTS
• Writing an if-else statement
int number = [self getNumberFromInput];
if (number > 9) {
NSLog(@”Number is a double-digit number”);
} else if (number == 0) {
NSLog(@”Number is not valid”);
} else {
NSLog(@”Number is a single digit number”);
}
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24. COMMON CLASSES
• Introduction to a few commonly used classes
• Not exhaustive
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25. NSOBJECT
• NSObject is the base class that every object in Objective-C
and Cocoa Touch inherits from
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26. NSSTRING
• NSString is an extremely commonly used class
• Type for ‘sentences’ or ‘words’
• NSString *myString = @”Hi There!”;
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27. NSARRAY
• Type for a collection or ‘array’ of objects grouped together
NSArray *weapons = [NSArray arrayWithObjects:@”rifle”, @”pistol”,
@”plasma gun”, nil];
Weapon *equippedPistol = [weapons objectAtIndex:1];
• Remember in programming we always start counting from 0
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28. NSDICTIONARY
• Type for a collection of objects indexed using key-value pairs
NSDictionary *playerData = [NSDictionary
dictionaryWithObjectsAndKeys:@”playerWeapons”, @”rifle”,
@”highScore”, 9214, @”numberOfLivesLeft”, 3, nil];
int livesLeft = [playerData objectForKey:@”numberOfLivesLeft”];
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29. THANK YOU!
Gabriel Lim
Getting Real Software Development
www.gettingrail.com
Monday, January 14, 13