Objective C
This is a primitive language used in Apple device application development (IOS/Macintosh). The base of this language is c. Objective –C is an easy to understand and object oriented programming language. Objective – c comes with library, development tool and OOPs.
The basic 3 parts are-
1. inter- face
Signature class. [*.h file]
2. implementation
Definition of a class.[*.m file]
3. Instantiation
instantiation of class by allocating memory.
Signature class. [*.h file]
2. implementation
Definition of a class.[*.m file]
3. Instantiation
instantiation of class by allocating memory.
It is a dynamic language. It supports open dynamic binding to create easy architecture for user interface.
Basic structure of a program-
#include <stdio.h>
//----Header file added------
int main(void)
{
printf("Hello!");
return ;
}
//----------Body Ends-----
Code file extension will be “.m”. It complies line by line. So if we need to call a function in other function, caller function should be bellow of called function.
#include <stdio.h>
-(void) called
{
}
-(void) caller
{
called();
}
int main(void)
{
caller();
return ;
}
For MAC ,Object compilation –
$ gcc -o hello hello.m \ -L /System/Library/Frameworks/Foundation.framework/Foundation
Run compiled code on MAC
$ ./hello
Compiler for Objective – c can be downloaded from - http://www.gnustep.org/experience/Windows.html. [For windows]
Key Words----
@interface | used to declare of class or interface. |
@implementation | used to define a class or category. |
@protocol | used to declare a formal protocol. |
@end | ends the declaration, definition, category or protocol. |
@private | Limits the scope of an instance variable to the class that declares it. |
@protected | Limits instance variable scope to declaring and inheriting classes. |
@public | Removes restrictions on the scope of instance variables. |
@try | Defines a block within which exceptions can be thrown. |
@throw | Throws an exception object. |
@catch | Catches an exception thrown within the preceding @try block. |
@finally | A block of code that is executed whether exceptions were thrown or not in a @try block. |
@class | Declares the names of classes defined elsewhere. |
@selector(method_name) | It returns the compiled selector that identifies method_name. |
@protocol(protocol_name) | Returns the protocol_name protocol (an instance of the Protocol class). (@protocol is also valid without (protocol_name) for forward declarations.) |
@encode(type_spec) | Yields a character string that encodes the type structure of type_spec. |
@"string" | Defines a constant NSString object in the current module and initializes the object with the specified 7-bit ASCII-encoded string. |
@synchronized() | Defines a block of code that must be executed only by one thread at a time. |
bool | It takes YES /NO |
'self' | |
‘Super’ |
Example code –
#include <objc/Object.h> @interface Car:Object{ //For instance variables } - (void)company; @end #include <stdio.h> @implementation Car - (void)company{ printf("BMW!\n");} @end #include <stdlib.h> int main(void){ id myCar; myCar =[Car new]; [myCar company]; [myCar free]; return EXIT_SUCCESS;}