How to use Object C in IOS?

Objective C is used in iOS development. It is built on top of the C programming language and which offers object oriented capabilities and a dynamic runtime. It includes all familiar elements like as primitive types i.e. int, float, char etc. structures, pointers, functions, and control flow constructs.
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You can also use standard C library routines which are declared in stdlib.h and stdio.h. In interface file class is declared and in implementation file class is defined.
Suppose there is a class IntellipaatClass.h then its interface file is:

@interface IntellipaatClass:NSObject {
// Declaration of class variable
}
// Declaration of class properties
// Declaration of class methods and instance methods
@end

 The implementation file IntellipaatClass.m is as follows:

@implementation IntellipaatClass
// Class methods
@end

 
Methods
In Objective C method is declared as follows –

-(returnType)Method_Name:(type_Name) variable1 :(type_Name)variable2;

 
Create Object
In Objective C objects are created as follows:

IntellipaatClass  *object_Name = [[IntellipaatClass alloc]init] ;

 
Class methods do not contain any objects and variables related with it. They can be accessed directly without creating objects for the class. Example is as follows:

+(void)Class_Method;

It can be accessed by using the class name like as follows −

[IntellipaatClass ClassMethod];

 
Instance methods – It can be accessed only after creating an object for the class. Memory is allocated to the instance variables.

-(void)InstanceMethod;

They can be access after creating an object like as follows –

IntellipaatClass  *objectName = [[IntellipaatClass alloc]init] ;
[objectName InstanceMethod];

 
Example

#import <Foundation/Foundation.h>
@interface SampleClass:NSObject -(void)sampleMethod;
@end
@implementation SampleClass -(void)sampleMethod{ NSLog(@"Hello, World! \n"); }
@end
int main() {
/* my first program in Objective-C */
SampleClass *sampleClass
= [[SampleClassalloc]init];
[sampleClasssampleMethod];
return 0;
}

 
Objects Communicate Through Messages
In Objective C one object sends a message to another object by calling a method on that object. If you have an object somePerson of class XYZPerson, you can send it the sayHello message like this:
Syntax:

[somePerson sayHello];

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