Objects, Classes, Methods, and Messages in Cocoa Programming
By: Aaron Hillegass in Cocoa Tutorials on 2010-09-03
All Cocoa programming is done using object-oriented techniques. This section very briefly reviews terms used in object-oriented programming. If you have not done any object-oriented programming before, I recommend that you read The Objective-C Language. (https://developer.apple.com/documentation/objectivec/nsobject.
What is an object? An object is like a C struct: It takes up memory and has variables inside it. The variables in an object are called instance variables. So when dealing with objects, the first questions we typically ask are: How do you allocate space for one? What instance variables does the object have? How do you destroy the object when you are done with it?
Some of the instance variables of an object will be pointers to other objects. These pointers enable one object to "know about" another object.
Classes are structures that can create objects. Classes specify the variables that the object has and are responsible for allocating memory for the object. We say that the object is an instance of the class that created it.
An object is better than a struct, because an object can have functions associated with it. We call the functions methods. To call a method, you send the object a message.
Add Comment
This policy contains information about your privacy. By posting, you are declaring that you understand this policy:
- Your name, rating, website address, town, country, state and comment will be publicly displayed if entered.
- Aside from the data entered into these form fields, other stored data about your comment will include:
- Your IP address (not displayed)
- The time/date of your submission (displayed)
- Your email address will not be shared. It is collected for only two reasons:
- Administrative purposes, should a need to contact you arise.
- To inform you of new comments, should you subscribe to receive notifications.
- A cookie may be set on your computer. This is used to remember your inputs. It will expire by itself.
This policy is subject to change at any time and without notice.
These terms and conditions contain rules about posting comments. By submitting a comment, you are declaring that you agree with these rules:
- Although the administrator will attempt to moderate comments, it is impossible for every comment to have been moderated at any given time.
- You acknowledge that all comments express the views and opinions of the original author and not those of the administrator.
- You agree not to post any material which is knowingly false, obscene, hateful, threatening, harassing or invasive of a person's privacy.
- The administrator has the right to edit, move or remove any comment for any reason and without notice.
Failure to comply with these rules may result in being banned from submitting further comments.
These terms and conditions are subject to change at any time and without notice.
- Data Science
- Android
- React Native
- AJAX
- ASP.net
- C
- C++
- C#
- Cocoa
- Cloud Computing
- HTML5
- Java
- Javascript
- JSF
- JSP
- J2ME
- Java Beans
- EJB
- JDBC
- Linux
- Mac OS X
- iPhone
- MySQL
- Office 365
- Perl
- PHP
- Python
- Ruby
- VB.net
- Hibernate
- Struts
- SAP
- Trends
- Tech Reviews
- WebServices
- XML
- Certification
- Interview
categories
Related Tutorials
Listing of files in a tar file in Mac OS X.
Listing of files in a zip file in Mac OS X.
Multithreading versus Multiprocessing in Mac OS X.
Using NSOpenGLView in Cocoa Programming in Mac
Garbage Collector in Cocoa Programming in Mac
Weak References in Mac Cocoa Programming
Web Services in Mac Cocoa Programming
Printing in Mac Cocoa Programming
What is Cocoa? A brief history of Cocoa.
Programming Language used in Cocoa Programming
Objects, Classes, Methods, and Messages in Cocoa Programming
Comments