StructureSwift

Character

A single extended grapheme cluster that approximates a user-perceived character.

@frozen struct Character

Overview

The Character type represents a character made up of one or more Unicode scalar values, grouped by a Unicode boundary algorithm. Generally, a Character instance matches what the reader of a string will perceive as a single character. Strings are collections of Character instances, so the number of visible characters is generally the most natural way to count the length of a string.

let greeting = "Hello! 🐥"
print("Length: \(greeting.count)")
// Prints "Length: 8"

Because each character in a string can be made up of one or more Unicode scalar values, the number of characters in a string may not match the length of the Unicode scalar value representation or the length of the string in a particular binary representation.

print("Unicode scalar value count: \(greeting.unicodeScalars.count)")
// Prints "Unicode scalar value count: 8"

print("UTF-8 representation count: \(greeting.utf8.count)")
// Prints "UTF-8 representation count: 11"

Every Character instance is composed of one or more Unicode scalar values that are grouped together as an extended grapheme cluster. The way these scalar values are grouped is defined by a canonical, localized, or otherwise tailored Unicode segmentation algorithm.

For example, a country’s Unicode flag character is made up of two regional indicator scalar values that correspond to that country’s ISO 3166-1 alpha-2 code. The alpha-2 code for The United States is “US”, so its flag character is made up of the Unicode scalar values "\u{1F1FA}" (REGIONAL INDICATOR SYMBOL LETTER U) and "\u{1F1F8}" (REGIONAL INDICATOR SYMBOL LETTER S). When placed next to each other in a string literal, these two scalar values are combined into a single grapheme cluster, represented by a Character instance in Swift.

let usFlag: Character = "\u{1F1FA}\u{1F1F8}"
print(usFlag)
// Prints "🇺🇸"

For more information about the Unicode terms used in this discussion, see the Unicode.org glossary. In particular, this discussion mentions extended grapheme clusters and Unicode scalar values.

Members

Typealiases

typealias UTF16View
A view of a character’s contents as a collection of UTF-16 code units. See String.UTF16View for more information
typealias UTF8View
A view of a character’s contents as a collection of UTF-8 code units. See String.UTF8View for more information
typealias UnicodeScalarView

RegexBuilder

typealias Output

Initializers

init(Unicode.Scalar)
Creates a character containing the given Unicode scalar value.
init(String)
Creates a character from a single-character string.
init(extendedGraphemeClusterLiteral: Character)
Creates a character with the specified value.
init(unicodeScalarLiteral: Self.ExtendedGraphemeClusterLiteralType)
Creates an instance initialized to the given value.

Instance Properties

var asciiValue: UInt8?
The ASCII encoding value of this character, if it is an ASCII character.
var customMirror: Mirror
A mirror that reflects the Character instance.
var debugDescription: String
A textual representation of the character, suitable for debugging.
var description: String
A textual representation of this instance.
var hexDigitValue: Int?
The numeric value this character represents, if it is a hexadecimal digit.
var isASCII: Bool
A Boolean value indicating whether this is an ASCII character.
var isCased: Bool
A Boolean value indicating whether this character changes under any form of case conversion.
var isCurrencySymbol: Bool
A Boolean value indicating whether this character represents a currency symbol.
var isHexDigit: Bool
A Boolean value indicating whether this character represents a hexadecimal digit.
var isLetter: Bool
A Boolean value indicating whether this character is a letter.
var isLowercase: Bool
A Boolean value indicating whether this character is considered lowercase.
var isMathSymbol: Bool
A Boolean value indicating whether this character represents a symbol that naturally appears in mathematical contexts.
var isNewline: Bool
A Boolean value indicating whether this character represents a newline.
var isNumber: Bool
A Boolean value indicating whether this character represents a number.
var isPunctuation: Bool
A Boolean value indicating whether this character represents punctuation.
var isSymbol: Bool
A Boolean value indicating whether this character represents a symbol.
var isUppercase: Bool
A Boolean value indicating whether this character is considered uppercase.
var isWhitespace: Bool
A Boolean value indicating whether this character represents whitespace, including newlines.
var isWholeNumber: Bool
A Boolean value indicating whether this character represents a whole number.
var unicodeScalars: Character.UnicodeScalarView
var utf16: Character.UTF16View
A UTF-16 encoding of self.
var utf8: Character.UTF8View
A UTF-8 encoding of self.
var wholeNumberValue: Int?
The numeric value this character represents, if it represents a whole number.

RegexBuilder

var regex: Regex<Character.Output>

RegexParser

var hasExactlyOneScalar: Bool
Whether this character is made up of exactly one Unicode scalar value.
var isOctalDigit: Bool
Whether this character represents an octal (base 8) digit, for the purposes of pattern parsing.
var isPatternWhitespace: Bool
Whether this character represents whitespace, for the purposes of pattern parsing.
var isWordCharacter: Bool
Whether this character represents a word character, for the purposes of pattern parsing.

Instance Methods

func hash(into: inout Hasher)
Hashes the essential components of this value by feeding them into the given hasher.
func lowercased() -> String
Returns a lowercased version of this character.
func uppercased() -> String
Returns an uppercased version of this character.
func write<Target>(to: inout Target)
Writes the character into the given output stream.

Type Operators

static func != (Self, Self) -> Bool
static func ... (Self) -> PartialRangeThrough<Self>
Returns a partial range up to, and including, its upper bound.
static func ... (Self) -> PartialRangeFrom<Self>
Returns a partial range extending upward from a lower bound.
static func ... (Self, Self) -> ClosedRange<Self>
Returns a closed range that contains both of its bounds.
static func ..< (Self) -> PartialRangeUpTo<Self>
Returns a partial range up to, but not including, its upper bound.
static func ..< (Self, Self) -> Range<Self>
Returns a half-open range that contains its lower bound but not its upper bound.
static func < (Character, Character) -> Bool
Returns a Boolean value indicating whether the value of the first argument is less than that of the second argument.
static func <= (Self, Self) -> Bool
Returns a Boolean value indicating whether the value of the first argument is less than or equal to that of the second argument.
static func == (Character, Character) -> Bool
Returns a Boolean value indicating whether two values are equal.
static func > (Self, Self) -> Bool
Returns a Boolean value indicating whether the value of the first argument is greater than that of the second argument.
static func >= (Self, Self) -> Bool
Returns a Boolean value indicating whether the value of the first argument is greater than or equal to that of the second argument.

Removed Members

Instance Properties

var customPlaygroundQuickLook: _PlaygroundQuickLook
A custom playground Quick Look for the Character instance.

Character

Overview

Members

Typealiases

RegexBuilder

Initializers

Instance Properties

RegexBuilder

RegexParser

Instance Methods

Type Operators

Conforms To

RegexBuilder

Removed Members

Instance Properties