Objective-c (NSString, BOOL, multi-file development)

NSString

Represents a string class in OC

%@ is the format character for objects in OC

printf cannot print objects in OC

By stringWithFormat: This class method, print the formatted string

Cases

int a = 10;

NSString * str = [NSString stringwithformat:@ "height is%i", a];

NSLog (@ "%@", str);

Calculates the length of a string by the method of seeking length in the nssting

The method of seeking length in OC, when printing, is in the character units of each country. A space is also a character

Example unsigned long OcL = [str length]; Length count character lengths

BOOL

The return value of type bool, the method name is usually preceded by the IS

The bool return value Yes,no either Yes 1, otherwise NO is 0.

OC Multi-File development

implement code with multiple files to increase readability and improve programming efficiency

Define a class divided into 2 files:. h files,. m files

. h file: A declaration of a member variable, method

. m file: implementation of a method

To use a class, you need the. h file for the #import class.

Objective-c (NSString, BOOL, multi-file development)