Objective-C LanguageDeclare class method and instance method

Introduction

Instance method are methods that are specific to particular classes. Instance methods are declared and defined followed by - (minus) symbol.

Class methods can be called by class name itself .Class methods are declared and defined by using + (plus)sign .

Syntax

  1. -(void)testInstanceMethod; //Class methods declare with "+" sign
  2. (void)classMethod;//instance methods declare with "-" sign

How to declare class method and instance method.

instance methods use an instance of a class.

@interface MyTestClass : NSObject

- (void)testInstanceMethod;
    
@end

They could then be used like so:

MyTestClass *object = [[MyTestClass alloc] init];
[object testInstanceMethod];

Class method can be used with just the class name.

@interface MyClass : NSObject

+ (void)aClassMethod;

@end

They could then be used like so:

[MyClass aClassMethod];

class methods are the convenience methods on many Foundation classes like [NSString's +stringWithFormat:] or NSArray's +arrayWithArray