Composition

• Strictly speaking only Objects are said to be composed.

• More primitive types like int, float, enum & struct are considered to be part of the Object.

• For Example CAR is composed of 1 ENGINE and 4 Tyres.

• If (self = [super init]) { is written to ensure super class is initialized. super init returns value of type id (generic object pointer).

• You can leave out curly braces in your class definition if you don't have any instance variables.