Objective-C Built-in Data Types and New Data Types

The variables you declare in Objective-C, Objective-C data types, must be a type that the compiler can recognize. Objective-C comes with a number of built-in data types, as well as mechanisms to create new ones, for programming your iPhone or Mac OS X applications.

Built-In Types

Type	Description	Size
char	A character	1 byte
int	An integer — a whole number	4 bytes
float	Single precision floating point number	4 bytes
Double	Double precision floating point number	8 bytes
short	A short integer	2 bytes
long	A double short	4 bytes
long long	A double long	8 bytes
BOOL	Boolean (signed char)	1 byte

Enumeration types

enum  typeName { identifier1, ... identifiern};

Identifiers are of constants of type int.

typedef

typedef  typeName  identifier;

Associates an identifier with a specific type.

Constants

const type  identifier  = value;
#define identifier value

Allows you to define names for constants.

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