String in Objective-C

Strings and Their Type

Strings are a fundamental concept in programming, used to represent sequences of text. In Objective-C, strings are objects that store sequences of characters. These characters can include letters, digits, symbols, or any other textual data. Objective-C provides various classes and methods for creating and manipulating strings, allowing for different ways of working with text.

Types of Strings

1. NSString: This is an immutable object that represents a sequence of characters. Once created, the string cannot be modified.
2. NSMutableString: This is a mutable object that allows changes after creation. You can add, remove, or modify characters.
3. CFString: This is a Core Foundation object used to represent sequences of Unicode characters.

Built-in Methods for Strings

Objective-C offers several classes and methods for creating and manipulating strings. Here are some commonly used ones:

Method	Purpose
NSString	Used to create an immutable string.
NSMutableString	Used to create a mutable string that can be changed.
length	Returns the length of the string.
stringWithFormat	Formats a string with specified values.
substringWithRange	Extracts a substring from the string based on a specified range.
isEqualToString	Compares two strings for equality.
stringByAppendingFormat	Appends a formatted string to the existing string.

Example 1: Creating a String with NSString

In this example, we create a string using the NSString class.

#import <Foundation/Foundation.h>

int main (int argc, const char * argv[]) {
    // Define a string
    NSString *greeting = @"Hello, Objective-C!";

    // Print the string
    NSLog(@"%@", greeting);

    return 0;
}

Output:

Hello, Objective-C!

Example 2: Formatting a String with Values

Here, we format a string by inserting a variable value into the string using stringWithFormat.

#import <Foundation/Foundation.h>

int main (int argc, const char * argv[]) {
    // Create an integer variable
    int appleCount = 12;

    // Format a string with a value
    NSString *formattedString = [NSString stringWithFormat:@"I have %d apples.", appleCount];

    // Print the formatted string
    NSLog(@"%@", formattedString);

    return 0;
}

Output:

I have 12 apples.