📖 Swift String Methods – Full Guide

1. Initialization

let emptyString = ""
let anotherEmptyString = String()
let fromCharacterArray = String(["H", "e", "l", "l", "o"])

2. Properties

let str = "Hello, Swift!"
print(str.isEmpty)
print(str.count)
print(str.startIndex)
print(str.endIndex)

3. Accessing Characters

for char in str {
    print(char)
}

print(str[str.startIndex])
print(str[str.index(before: str.endIndex)])

4. Modifying Strings

Inserting

var greeting = "Hello"
greeting.insert("!", at: greeting.endIndex)

Removing

greeting.remove(at: greeting.index(before: greeting.endIndex))
greeting.removeSubrange(greeting.index(greeting.endIndex, offsetBy: -2)..<greeting.endIndex)

5. Concatenation

let first = "Hello"
let second = " World"
let result = first + second

var greetingAgain = "Hi"
greetingAgain += " there"

6. String Interpolation

let name = "John"
let age = 30
let intro = "My name is \(name) and I am \(age) years old."

7. Prefix and Suffix Checks

let filename = "photo.jpg"
print(filename.hasPrefix("photo"))
print(filename.hasSuffix(".jpg"))

8. Changing Case

let text = "Swift Programming"
print(text.uppercased())
print(text.lowercased())
print(text.capitalized)

9. Finding Substrings

let message = "Hello, world!"
if let range = message.range(of: "world") {
    print(message[range])
}

10. Replacing Substrings

var welcome = "Hello, playground"
welcome = welcome.replacingOccurrences(of: "playground", with: "world")

11. Splitting Strings

let sentence = "apple,banana,cherry"
let fruits = sentence.split(separator: ",")
for fruit in fruits {
    print(fruit)
}

12. Joining Strings

let words = ["Swift", "is", "awesome"]
let joined = words.joined(separator: " ")

13. Trimming Whitespaces and Newlines

let messy = "   Hello World! \n"
let cleaned = messy.trimmingCharacters(in: .whitespacesAndNewlines)

14. Substrings and Slicing

let str2 = "Hello, Swift!"
let index = str2.firstIndex(of: ",") ?? str2.endIndex
let substring = str2[..<index]
let newString = String(substring)

15. Contains Check

let phrase = "I love Swift programming."
print(phrase.contains("Swift"))

16. Comparing Strings

let a = "apple"
let b = "Apple"

print(a == b)
print(a.lowercased() == b.lowercased())

17. Advanced Methods

dropFirst() and dropLast()

let greet = "Hello"
let dropped = greet.dropFirst()

prefix(_:) and suffix(_:)

let text2 = "abcdef"
print(text2.prefix(3))
print(text2.suffix(2))

split(whereSeparator:)

let complex = "Swift;Kotlin;Java"
let parts = complex.split { $0 == ";" }

18. Localization (Case Insensitive)

let city = "München"
print(city.lowercased())
print(city.folding(options: .diacriticInsensitive, locale: .current))

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