iOS course day 1

Components of Computer System
RAM
(Random Access Memory)
Disk
(Hard Disk Drive)
CPU
(Central Processing Unit)

How a computer reads our code
Objective-C
This is what our source code is written in.
Compiler
Object Code
(otherwise known as Binary)
eg: 0110001010110101

RAM:
The place where applications run. Computers are
restrained by memory and 80% of program crashes
relate to memory.
Disk:
This is where applications that are not running reside
along with user data.
CPU:
The processor that runs and executes programs

iOS Stack
Core OS
Core Services
Media
Coca Touch
High Level
(Objective C)
Low Level
(C)

Tools
Integrated Development Environment (IDE): Xcode
(Code Editor)
Programming Languages: C, C++, Objective-C and Swift
Main
Other Programs
Instruments, Memory Allocation & Leaks

Step 1: Start a new project in Xcode
Step 2: Navigate to the App Delegate.m file
Step 3: Add the following code:
Step 4: Build and Run!

Variables: Variables are a container that holds some kind of
value.
for example: int myVar = 1;
We now have a variable called myVar and its value is equal to 1;

Functions: Functions are the way a system performs some kind
of action. These can either return a value or not.
Example 1:
int myVar = 1;
[self myFunction];
(void)myFunction
{
myVar = 2;
}
Example 2:
int myVar = 1;
myVar = [self myFunction];
(int)myFunction
{
return 2;
}

Parameters: Parameters are variables passed into a function for
it to do some computation with.
Example 1:
int myVar = 1;
int otherNumber = 20;
int total = [self addNumbers: myVar and: otherNumber];
(int)addNumbers:(int)firstNumber and:(int)secondNumber
{
int result = firstNumber + secondNumber;
return variable;
}
total would equal 21.

C Programming in 1 Slide
Integer
Loops
Array
If Then
Switch
Struct

Preprocessor
Processes the source code before it gets compiled.
Preprocessor performs a search &replace to all occurrences of the name with its value.
Loads all the content of a file into the current file. - Watch out for circular dependancies!
Objective-C: Loads all the content of a file into the current file. Automatically handles circular dependanci
Compiler Specific instructions. Often used as a way for you to easily navigate the code file.

Classes
Objective C is object orientated
This means the source code is split up into files called clas
An Objective C Class has Two Files:
A interface file (.h)
(otherwise known as a header)
A Implementation file (.m)
@implementation ViewController
@end
@interface ViewController : UIViewController
@end
A Header is the public file.
It is where we declare methods and
variables for use by other classes
The Implementation file is where
the logic for the declared methods
goes.

Objective-C: Sending Messages
We want to be able to send messages to a class when tryi
The way we do that is like:
[myClass doSomething];

With Parameters
If we want to call a function with Parameters we call:
[myClass doSomething: @“aString”];

With Multiple Parameters
If we want to call a function with Parameters we call:
[myClass doSomethingWith This:@“FirstString”
andThis:@“SecondString”];

Objective-C: Instantiating Objects
When we want to use a class we need to create a
instance of that class in memory. We do that by
calling the classes init method, which stands for
instantiate.
MyClass *object = [[MyClass alloc]init];
NOTE: we called two methods on this alloc and init.
‘alloc’ is the function that allocates the memory
required for the object and then init sets it up.

Objective-C: More Classes
When we alloc and init a class the system sets us
up an instance of our class and then returns a
pointer to its location in memory.
You can have multiple instances of a class.
There are some classes called singletons however. This
means that there is only one of them in the application. An
example of this is the App Delegate.

Objective-C: Singleton Classes
This is something you will come across more as
you go forward however the main one you will
encounter is your AppDelegate.
One use of a singleton is if you have a variable that
needs to be accused through the app then you
would declare it there.

Objective-C: Memory Management
Since were are allocating memory all over the
place we need to clear this up so that other parts of
the program can use it. If we don’t its called a
memory leak.
The good news is that these days Apple has
created something called Automatic Reference
Counting (ARC) which does this for us. We will
cover this more later.

Objective-C: Getters / Setters
Getters and Setters are fairly self explanatory. They
are the methods you would call on your class to get
a value or set a value.
Example:
[object setRating:9.5];
double theRating = [object rating];

Interface (.h)

Implementation (.m)

Objective-C: Properties
More Good News!!!
Apple has created something called properties.
When you declare on of these in the implementation file
it will create the getters and setters behind the scene
We’ll look at these in more depth in the next slide but the main thing here is to see how th

Objective-C: Properties
How do we call a property?
We use something called Dot Notation
object.rating = 9.5;

Objective-C: Properties / Memory
Ok back to Memory as Promised
As promised here is the rest of the memory stuff to get to grips with. With ARC iOS will k
This makes our life much easier however we need to help it a bit by telling it what needs
An object can have any of the following:
Strong
Weak
Nonatomic
Atomic

Strong: Keeps the object around as long as
the class is alive and pointing to it.
Weak: Keeps the object around as long as
another object is pointing to it strongly.
Objective-C: Properties / Memory II
Atomic/ Nonatomic:
-atomic is the default, which provides support for using this property
in multiple treads (at no extra cost).

Objective-C: Foundation Classes
In Objective-C we have the same data types as in other lang
Common Objective C object types:
NSString
NSArray
NSDictionary
NSDate
NSNumber
NSData
Immutable
NSMutableString
NSMutableArray
NSMutableDictionary
NSDate
NSNumber
NSData
Mutable

Objective-C: Foundation Classes II
Each one of the types in objective C have a class associate
In those classes are properties such as ‘length’ for NSString
As well as Getters and Setters.

Inheritance and Polymorphism
Inheritance is something that you will encounter at all over ob
Its actually more simple that it looks:
(known as a parent class). This means that the class has all t

Vehicle
Car BattleShip
Vehicle.h
-(void)move
-(void)turnLeft
-(void)turnRight
BattleShip.h
-(void)shoot
Car.h
-(void)Park

instance of a class can also be treated as an instance of any

Coca-Touch: Model View Controller
In iOS the standard way to design your app is using someth
It breaks down like this:
Model: Data and Business Rules
View: User Interface Elements
Controller: Behaviour and referee between the model and th

Coca-Touch: Model View Controller
Model View
Controller
UI Storyboard
ViewController.h
Concert.h
Model data source
could be:
File System
Database
Web Service
Core Data

• String with format
• App Coda
• Ray Weinerlich

iOS course day 1

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iOS course day 1