What is self in ObjC? When should i use it?

by

self refers to the instance of the current class that you are working in, and yes, it is analagous to this in Java.

You use it if you want to perform an operation on the current instance of that class. For example, if you are writing an instance method on a class, and you want to call a method on that same instance to do something or retrieve some data, you would use self:

int value = [self returnSomeInteger];

This is also often used for accessor methods on an instance (i.e. setters and getters) especially with setter methods, if they implement extra functionality rather than just setting the value of an instance variable, so that you do not have to repeat that code over and over when you want to set the value of that variable, for example:

[self setSomeVariable:newValue];

One of the most common uses of self is during initialization of a class. Sample code might look like:

- (id)init
{
    self = [super init];

    if(self!=nil) {
        //Do stuff, such as initializing instance variables
    }

    return self;
}

This invokes the superclass’s (via super) initializer, which is how chained initialization occurs up the class hierarchy. The returned value is then set to self, however, because the superclass’s initializer could return a different object than the superclass.

More Related Contents:

  1. When to access properties with ‘self’
  2. How to call an Objective-C Method from a C Method?
  3. How change the size of sprite in cocos2d? [closed]
  4. Cannot hide status bar in iOS7
  5. Best way to define private methods for a class in Objective-C
  6. Would it be beneficial to begin using instancetype instead of id?
  7. Objective-C Introspection/Reflection
  8. Add animated Gif image in Iphone UIImageView
  9. NSString tokenize in Objective-C
  10. Why does rand() % 7 always return 0?
  11. Are Swift variables atomic?
  12. Save NSDictionary to plist
  13. iOS taking photo programmatically
  14. Are classes objects in Objective-C?
  15. Does ARC work with Core Graphics objects?
  16. How does rand() work? Does it have certain tendencies? Is there something better to use?
  17. What makes a keychain item unique (in iOS)?
  18. Class variable defined at @implementation rather than @interface?
  19. How to get the reference count of an NSObject?
  20. RootViewController Switch Transition Animation
  21. How to escape double quotes in string?
  22. Why does ARC retain method arguments?
  23. Singleton in iOS 5?
  24. Creating a ZIP archive from a Cocoa application
  25. How do I pass multiple parameters in Objective-C?
  26. iOS: Compare two NSDate-s without time portion
  27. NSString instance reports its class as NSCFString
  28. NSMutableAttributedString add different alignments
  29. Comparing objects in Obj-C
  30. viewDidLoad in NSViewController?

Leave a Comment