The document provides an overview of Objective-C basics including the Objective-C language, build and runtime, classes, objects, methods, and data encapsulation. It discusses the three main parts of an Objective-C class which are the @interface section for declarations, the @implementation section for definitions, and the program section for problem solving code. Methods are explained as actions performed on class instances that can affect the object's state. The document also covers how to create objects from classes, access methods, and encapsulate data to hide instance variables from direct access.

1. Objective-C basic
Chorn Charly
Leang Bunrong
Cheng Udam
Kan Vichhai
Srou Chanthorn
Em Vy
Seth Sambo
Chea Socheat

2. Content
• Objective–C Language
• Build and Run time in Objective-C Programming
• What is an Object, anyway?
• Accessing Methods
• Classes, Objects, and Methods
• The @interface Section
• The @implementation Section
• The program Section
• Accessing variable and data encapsulation

3. Objective–C Language
• Objective – C is supper of C. It is easy to mix C language and C++ language. And add
more features (OOP) to C language. So objective- C is almost Completed OOP.
• File extension of objctive-C

4. Build and Run time in Objective-C Programming
• /usr/lib/libobjc.A.dylib is shared library provides support for the dynamic properties of
the Objective-C language, and as such is linked to by all Objective-C applications. All
functions of our Apps are implement in this library.
• GNU Compiler Collection provides a different implementation with a similar API.this
mean that the OS X implementation of the Objective-C runtime library is unique to the
Mac. When use for the other platforms GNU Compiler Collection is controller (how to
create Protocol Count,Structure...etc..) .
• Note: GNUStep or NextStep or Cocao FrameWork is FramWork to build App. Basic
object from objective –C base framework and compiled with GCC compiler(target
system).

5. Build and Run time in Objective-C Programming (cont.)
1st
Sending
Message
Protocol and structure for
other platforms
Protocol and structure for
Mac OS
Execute
file(.m)
GCC
Compiler
GNU Compiler
Collection
2nd
libobjc.A.dylib(Library)
3rd

6. What is an object?
• Everything is object => object is provided by class
• Class => object
• So in objective-C we have a class and we can create object, this concept we call OOP
• How to create an object in objective-C?
• ClassName *obj = [[ClassName alloc]init];
• Example: we have a class name ‘Machine’ so we want to create object in other class
We can do that: Machine *machine = [[Machine alloc]init]; or Machine *machine = [[Machine new]init];

7. What is an object?
• Processing of creating object
machine
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Machine *machine = [[Machine alloc]init];
Initialize value it is look like constructor in java

8. Accessing Methods
• Method is the actions that performed on the instance of the class or to the class itself.
Applying a method to an object can affect the state of that object.
• Syntax for applying method to classes and instances: [ Class Or Instance method ];
• Similar with now you are sending a message to receiver: [ receiver message ];
• Example: we have a class name: Car and there is a method washCar
[yourCar washCar]; or [Car washCar];
Instance object Class
• yourCar is a receiver and wash is the message.

9. Classes, Objects, and Methods
• Now let imagine that you are working with fraction. You may need to deal with adding,
subtracting, multiplying, and so on.
• If you don’t know what is class, how to create it you program will be looked like:
#import <Foundation/Foundation.h>
int main(int argc, char * argv[] ){
@autoreleasepool{
int num1=1, num2=3;
NSLog(@”%i/%i”,num1,num2);
}
return 0;
}

10. Classes, Objects, and Methods
• To create fraction 1/3, we stored 1 in num1 and 3 in num2
• For now, let create our own Fraction class to make fraction
#import <Foundation/Foundation.h>
//---- @interface section ----
@interface Fraction: NSObject
-(void) print;
-(void) setNumerator: (int) n;
-(void) setDenominator: (int) d;
• @end

11. Classes, Objects, and Methods
@implementation Fraction {
int numerator;
int denominator;
}
-(void) print {
NSLog (@"%i/%i", numerator, denominator);
}
-(void) setNumerator: (int) n{
numerator = n;
}
-(void) setDenominator: (int) d{
denominator = d;
}
@end

12. Classes, Objects, and Methods
int main (int argc, char * argv[]) {
@autoreleasepool {
Fraction *myFraction;
myFraction = [Fraction alloc];
myFraction = [myFraction init];
[myFraction setNumerator: 1];
[myFraction setDenominator: 3];
NSLog (@"The value of myFraction is:");
[myFraction print];
}
return 0;
}
• After we created our own Fraction class we can see that we have 3 part such as:
• @interface
• @implementation
• Program section

13. interface section
+When you define a new class, you have to tell the objective-compiler where the class came from(type
of class) naming convention class is begin with an uppercase letter.
+All method and data member in the class is declaration in the interface section between
@interface and @end. for data member declaration we need to add {} and methods is outside the {}
@interface NewClassName: ParentClassName
{
//Here is data member declaration (state)
}
//here is propertyAndMethodDeclarations (behavior);
@end

14. interface section cont…
• objective c is case-sensitive. The method declaration leading sign (-) or (+) tells the
objective-c compiler that the method is an instance method or class method. Following
the leading sigh is method return type, this is tell the compiler after method complete
what type of data will be return. For return the value we used with the "return" keyword.
Following the return type is the class name , you can see in the class convention part.
After the class name is the arguments and the data type of argument, this argument will
be passed in the method definition.

15. implementation section
• the @implementation section contains the actual code for the method we declared in
the @interface section. We can say in the @interface section is place for declaration
instance variables , instance methods and class methods of the object. And the
@implementation section is a place for method definitions of class methods and
instance methods.
@implementation NewClassName:NSObject{
//memberDeclarations;
}
//methodDefinitions;
@end
Note
The class name is the same name that was used for
the class in the @interface section.
you can trailing Colin followed by parent class name
but this is optional.

16. The programming section
• The programming section in Objective-C is the area that contained code to solve particular
problem.
• It is in the main method in Objective-C class
Example
/*Programming section*/
int main(int argc, char *argv[]){
@autoreleasepool{
// problem solving here
}
}

17. Accessing variable and data encapsulation
• Accessing variable
• Class method can dealing with the class itself.
Example
@implementation Fraction{
int numerator;
}
-(void)setNumerator : (int) n
{
numerator = n;
}
@end

18. The programming section(Cont.)
• Data Encapsulation
• As example above variable numerator can not access from somewhere else because it is
hidden.
• To retrieve value from the value of that instance variable, you need to write as the example
below.
Example
@implementation Fraction{
-(int)numerator;
}
// its definition
-(int)numerator
{
return numerator;
}
@end

19. Thank you