What is the difference between class and instance methods?

by

Like most of the other answers have said, instance methods use an instance of a class, whereas a class method can be used with just the class name. In Objective-C they are defined thusly:

@interface MyClass : NSObject

+ (void)aClassMethod;
- (void)anInstanceMethod;

@end

They could then be used like so:

[MyClass aClassMethod];

MyClass *object = [[MyClass alloc] init];
[object anInstanceMethod];

Some real world examples of class methods are the convenience methods on many Foundation classes like NSString‘s +stringWithFormat: or NSArray‘s +arrayWithArray:. An instance method would be NSArray‘s -count method.

More Related Contents:

  1. Use of alloc init instead of new
  2. Method Syntax in Objective-C
  3. How do I declare class-level properties in Objective-C?
  4. What’s the difference between “class method” and “static method”?
  5. Class methods which create new instances
  6. What is the difference between inheritance and Categories in Objective-C
  7. Git – how do I view the change history of a method/function?
  8. When should I call super?
  9. Call instance method from class method
  10. What is Protocol Oriented Programming in Swift? What added value does it bring?
  11. Checking Objective-C block type?
  12. What happens if two ObjC categories override the same method?
  13. How do I pass multiple parameters in Objective-C?
  14. Implement a pure virtual method in Objective-C
  15. Should I subclass the NSMutableArray class
  16. Objective C Equivalent of PHP’s “Variable Variables” [duplicate]
  17. Shortcuts in Objective-C to concatenate NSStrings
  18. How does the new automatic reference counting mechanism work?
  19. Gaining root permissions on iOS for NSFileManager (Jailbreak)
  20. What’s the best way to develop a sideswipe menu like the one in Facebook’s new iOS app?
  21. Apple Mach-O Linker Error when compiling for device
  22. Difference between @interface definition in .h and .m file
  23. iOS – Merging two images of different size
  24. How do I create a temporary file with Cocoa?
  25. How to escape double quotes in string?
  26. Singleton in iOS 5?
  27. Objective C – Custom view and implementing init method?
  28. NSString – Convert to pure alphabet only (i.e. remove accents+punctuation)
  29. WaveForm on IOS
  30. Looping using NSRange

Leave a Comment