Strings in Objective-C

Strings are a fundamental concept in programming, and they are used to represent text in many different applications. In Objective-C, a string is an object that represents a sequence of characters. A string can be created using several built-in classes and methods, which allow you to manipulate the text and perform various operations. A string is a sequence of characters, such as letters, digits, and symbols. In Objective-C, a string is an object that represents this sequence of characters. A string can be created using a class, which is a blueprint for creating objects. Once you have created a string object, you can use various methods to manipulate the text and perform operations on it. Objective-C provides several types of strings that can be used to create and manipulate text.

Types of Strings

• NSString: It is an immutable object that represents a sequence of characters. Once created, it cannot be changed. NSString is the most commonly used type of string in Objective-C.
• NSMutableString: It is a mutable object that represents a sequence of characters. It can be modified after creation, and new characters can be added or removed.
• CFString: It is a Core Foundation object that represents a sequence of Unicode characters.

Built-in Methods for Strings

Objective-C provides several built-in classes and methods for creating and manipulating strings. Some of the most commonly used methods are:

Methods	Purpose
NSString	It is an immutable class used to create a string that cannot be changed once created.
NSMutableString	It is a mutable class used to create a string that can be changed after it is created.
length	It is a method used to get the length of the string.
stringWithFormat	It is used to format a string with values.
substringWithRange	It is a method used to get a substring of the string.
isEqualToString	It is a method used to compare two strings for equality.
stringByAppendingFormat	It is a method used to append a formatted string to the end of a string.

Example 1:

In the following example, we are going to create a string using NSString.

ObjectiveC

#import <Foundation/Foundation.h>

int main (int argc, const char * argv[]){

// define string
NSString *myString = @"Hello, World!";

// print result
NSLog(@"%@", myString);

   return 0;
}

When the preceding code is compiled and run, the following output is obtained:

Example 2:

In the following example, we are going to format a string with values using stringWithFormat.

ObjectiveC

#import <Foundation/Foundation.h>

int main (int argc, const char * argv[]){

// create a int variable
int count = 10;

// format a string with a value using stringWithFormat
NSString *myFormattedString = [NSString stringWithFormat:@"I have %d apples.", count];

// print result
NSLog(@"%@", myFormattedString);

return 0;
}

When the preceding code is compiled and run, the following output is obtained:

Example 3:

In the following example, we create and manipulate strings in Objective-C:

ObjectiveC

#import <Foundation/Foundation.h>

int main (int argc, const char * argv[]){

// Create a string using the NSString class
NSString *myString = @"Hello, World!";

// Get the length of the string
NSUInteger length = [myString length];

// Get a substring of the string
NSString *substring = [myString substringWithRange:NSMakeRange(7, 5)];

// Compare the string to another string
BOOL isEqual = [myString isEqualToString:@"Hello, World!"];

// Create a mutable string using the NSMutableString class
NSMutableString *mutableString = [NSMutableString stringWithString:@"Hello"];

// Append a string to the end of the mutable string
[mutableString appendString:@" World!"];

// Add two strings together
NSString *string1 = @"Hello";
NSString *string2 = @"World";
NSString *result = [string1 stringByAppendingFormat:@" %@", string2];

// Print the results to the console
NSLog(@"Original string: %@", myString);
NSLog(@"Length of string: %lu", length);
NSLog(@"Substring of string: %@", substring);
NSLog(@"String is equal: %d", isEqual);
NSLog(@"Mutable string: %@", mutableString);
NSLog(@"Concatenated string: %@", result);


return 0;
}

When the preceding code is compiled and run, the following output is obtained: