String Methods in

About String Methods

Working with string is a common task in programming. Therefore Swift provides a variety of methods to manipulate strings. This document will cover some of the most common string methods and properties, some of these require the import of the Foundation framework.

components(separatedBy:)

When you want to split a string into an array of substrings, you can use the components(separatedBy:) method. So say you would want to get every word in a sentence, you can use the space character as the separator.

let sentence = "Hello, world!"
let words = sentence.components(separatedBy: " ")
print(words) // Prints ["Hello,", "world!"]

hasPrefix(_:), hasSuffix(_:)

When you want to check if a string starts or ends with a certain substring, you can use the hasPrefix(_:) and hasSuffix(_:) methods. Both of these methods take a string as an argument and return a boolean value indicating whether the string starts or ends with the specified substring.

let greeting = "Hello, world!"
print(greeting.hasPrefix("Hello"))  // Prints true
print(greeting.hasSuffix("world!")) // Prints true

lowercased, uppercased, capitalized

When you want to change the case of a string, you can use the lowercased, uppercased, and capitalized properties. The lowercased property returns a new string with all characters in lowercase, the uppercased property returns a new string with all characters in uppercase, and the capitalized property returns a new string with the first character of each word capitalized.

let greeting = "hello, world!"
print(greeting.lowercased)  // Prints "hello, world!"
print(greeting.uppercased)  // Prints "HELLO, WORLD!"
print(greeting.capitalized) // Prints "Hello, World!"

replacingOccurrences(of:with:)

When you want to replace all occurrences of a substring in a string with another substring, you can use the replacingOccurrences(of:with:) method. This method takes two strings as arguments: the substring to be replaced and the substring to replace it with. It returns a new string with all occurrences of the specified substring replaced.

let greeting = "Hello, world!"
let newGreeting = greeting.replacingOccurrences(of: "world", with: "Swift")
print(newGreeting) // Prints "Hello, Swift!"

joined(separator:)

This isn't a method of the String type, but rather of the Array type. When you want to join an array of strings into a single string with a specified separator, you can use the joined(separator:) method. This method takes a string as an argument and returns a new string with all elements of the array joined together, separated by the specified string.

let words = ["Hello", "world"]
let sentence = words.joined(separator: ", ")
print(sentence) // Prints "Hello, world"