Structure

String.UnicodeScalarView

A view of a string’s contents as a collection of Unicode scalar values.

Declaration

struct UnicodeScalarView

Overview

You can access a string’s view of Unicode scalar values by using its unicodeScalars property. Unicode scalar values are the 21-bit codes that are the basic unit of Unicode. Each scalar value is represented by a Unicode.Scalar instance and is equivalent to a UTF-32 code unit.

let flowers = "Flowers 💐"
for v in flowers.unicodeScalars {
    print(v.value)
}
// 70
// 108
// 111
// 119
// 101
// 114
// 115
// 32
// 128144

Some characters that are visible in a string are made up of more than one Unicode scalar value. In that case, a string’s unicodeScalars view contains more elements than the string itself.

let flag = "🇵🇷"
for c in flag {
    print(c)
}
// 🇵🇷

for v in flag.unicodeScalars {
    print(v.value)
}
// 127477
// 127479

You can convert a String.UnicodeScalarView instance back into a string using the String type’s init(_:) initializer.

let favemoji = "My favorite emoji is 🎉"
if let i = favemoji.unicodeScalars.firstIndex(where: { $0.value >= 128 }) {
    let asciiPrefix = String(favemoji.unicodeScalars[..<i])
    print(asciiPrefix)
}
// Prints "My favorite emoji is "

Topics

Initializers

init()

Creates an empty view instance.

init<S>(S)

Creates a new instance of a collection containing the elements of a sequence.

init(repeating: Unicode.Scalar, count: Int)

Creates a new collection containing the specified number of a single, repeated value.

Instance Properties

var count: Int

The number of elements in the collection.

var customMirror: Mirror

Returns a mirror that reflects the Unicode scalars view of a string.

var endIndex: String.UnicodeScalarView.Index

The “past the end” position—that is, the position one greater than the last valid subscript argument.

var first: Unicode.Scalar?

The first element of the collection.

var indices: DefaultIndices<String.UnicodeScalarView>

The indices that are valid for subscripting the collection, in ascending order.

var isEmpty: Bool

A Boolean value indicating whether the collection is empty.

var last: Unicode.Scalar?

The last element of the collection.

var lazy: LazySequence<String.UnicodeScalarView>

A sequence containing the same elements as this sequence, but on which some operations, such as map and filter, are implemented lazily.

var startIndex: String.UnicodeScalarView.Index

The position of the first Unicode scalar value if the string is nonempty.

var underestimatedCount: Int

A value less than or equal to the number of elements in the collection.

Instance Methods

func allSatisfy((Unicode.Scalar) -> Bool) -> Bool

Returns a Boolean value indicating whether every element of a sequence satisfies a given predicate.

func append(Unicode.Scalar)

Appends the given Unicode scalar to the view.

func append<S>(contentsOf: S)

Appends the Unicode scalar values in the given sequence to the view.

func append<S>(contentsOf: S)

Adds the elements of a sequence or collection to the end of this collection.

Beta
func compactMap<ElementOfResult>((Unicode.Scalar) -> ElementOfResult?) -> [ElementOfResult]

Returns an array containing the non-nil results of calling the given transformation with each element of this sequence.

func contains(Unicode.Scalar) -> Bool

Returns a Boolean value indicating whether the sequence contains the given element.

func contains(where: (Unicode.Scalar) -> Bool) -> Bool

Returns a Boolean value indicating whether the sequence contains an element that satisfies the given predicate.

func count(where: (Unicode.Scalar) -> Bool) -> Int

Returns the number of elements in the sequence that satisfy the given predicate.

Beta
func distance(from: String.Index, to: String.Index) -> Int

Returns the distance between two indices.

func drop(while: (Unicode.Scalar) -> Bool) -> Substring.UnicodeScalarView

Returns a subsequence by skipping elements while predicate returns true and returning the remaining elements.

func dropFirst(Int = 1) -> Substring.UnicodeScalarView

Returns a subsequence containing all but the given number of initial elements.

func dropLast(Int) -> Substring.UnicodeScalarView

Returns a subsequence containing all but the specified number of final elements.

func elementsEqual<OtherSequence>(OtherSequence) -> Bool

Returns a Boolean value indicating whether this sequence and another sequence contain the same elements in the same order.

func elementsEqual<OtherSequence>(OtherSequence, by: (Unicode.Scalar, OtherSequence.Element) -> Bool) -> Bool

Returns a Boolean value indicating whether this sequence and another sequence contain equivalent elements in the same order, using the given predicate as the equivalence test.

func enumerated() -> EnumeratedSequence<String.UnicodeScalarView>

Returns a sequence of pairs (n, x), where n represents a consecutive integer starting at zero and x represents an element of the sequence.

func filter((Unicode.Scalar) -> Bool) -> String.UnicodeScalarView

Returns a new collection of the same type containing, in order, the elements of the original collection that satisfy the given predicate.

func first(where: (Unicode.Scalar) -> Bool) -> Unicode.Scalar?

Returns the first element of the sequence that satisfies the given predicate.

func firstIndex(of: Unicode.Scalar) -> String.Index?

Returns the first index where the specified value appears in the collection.

func firstIndex(where: (Unicode.Scalar) -> Bool) -> String.Index?

Returns the first index in which an element of the collection satisfies the given predicate.

func flatMap<SegmentOfResult>((Unicode.Scalar) -> SegmentOfResult) -> [SegmentOfResult.Element]

Returns an array containing the concatenated results of calling the given transformation with each element of this sequence.

Beta
func forEach((Unicode.Scalar) -> Void)

Calls the given closure on each element in the sequence in the same order as a for-in loop.

func formIndex(String.Index, offsetBy: Int)

Offsets the given index by the specified distance.

func formIndex(String.Index, offsetBy: Int, limitedBy: String.Index) -> Bool

Offsets the given index by the specified distance, or so that it equals the given limiting index.

func formIndex(after: String.Index)

Replaces the given index with its successor.

func formIndex(before: String.Index)

Replaces the given index with its predecessor.

func index(String.Index, offsetBy: Int) -> String.Index

Returns an index that is the specified distance from the given index.

func index(String.Index, offsetBy: Int, limitedBy: String.Index) -> String.Index?

Returns an index that is the specified distance from the given index, unless that distance is beyond a given limiting index.

func index(of: Unicode.Scalar) -> String.Index?

Returns the first index where the specified value appears in the collection.

Deprecated
func insert(Unicode.Scalar, at: String.Index)

Inserts a new element into the collection at the specified position.

Beta
func insert<C>(contentsOf: C, at: String.Index)

Inserts the elements of a sequence into the collection at the specified position.

Beta
func last(where: (Unicode.Scalar) -> Bool) -> Unicode.Scalar?

Returns the last element of the sequence that satisfies the given predicate.

func lastIndex(of: Unicode.Scalar) -> String.Index?

Returns the last index where the specified value appears in the collection.

func lastIndex(where: (Unicode.Scalar) -> Bool) -> String.Index?

Returns the index of the last element in the collection that matches the given predicate.

func lexicographicallyPrecedes<OtherSequence>(OtherSequence) -> Bool

Returns a Boolean value indicating whether the sequence precedes another sequence in a lexicographical (dictionary) ordering, using the less-than operator (<) to compare elements.

func lexicographicallyPrecedes<OtherSequence>(OtherSequence, by: (Unicode.Scalar, Unicode.Scalar) -> Bool) -> Bool

Returns a Boolean value indicating whether the sequence precedes another sequence in a lexicographical (dictionary) ordering, using the given predicate to compare elements.

func makeIterator() -> String.UnicodeScalarView.Iterator

Returns an iterator over the Unicode scalars that make up this view.

func map<T>((Unicode.Scalar) -> T) -> [T]

Returns an array containing the results of mapping the given closure over the sequence’s elements.

func max() -> Unicode.Scalar?

Returns the maximum element in the sequence.

func max(by: (Unicode.Scalar, Unicode.Scalar) -> Bool) -> Unicode.Scalar?

Returns the maximum element in the sequence, using the given predicate as the comparison between elements.

func min() -> Unicode.Scalar?

Returns the minimum element in the sequence.

func min(by: (Unicode.Scalar, Unicode.Scalar) -> Bool) -> Unicode.Scalar?

Returns the minimum element in the sequence, using the given predicate as the comparison between elements.

func popLast() -> Unicode.Scalar?

Removes and returns the last element of the collection.

func prefix(Int) -> Substring.UnicodeScalarView

Returns a subsequence, up to the specified maximum length, containing the initial elements of the collection.

func prefix(through: String.Index) -> Substring.UnicodeScalarView

Returns a subsequence from the start of the collection through the specified position.

func prefix(upTo: String.Index) -> Substring.UnicodeScalarView

Returns a subsequence from the start of the collection up to, but not including, the specified position.

func prefix(while: (Unicode.Scalar) -> Bool) -> Substring.UnicodeScalarView

Returns a subsequence containing the initial elements until predicate returns false and skipping the remaining elements.

func randomElement() -> Unicode.Scalar?

Returns a random element of the collection.

func randomElement<T>(using: T) -> Unicode.Scalar?

Returns a random element of the collection, using the given generator as a source for randomness.

func reduce<Result>(Result, (Result, Unicode.Scalar) -> Result) -> Result

Returns the result of combining the elements of the sequence using the given closure.

func reduce<Result>(into: Result, (inout Result, Unicode.Scalar) -> ()) -> Result

Returns the result of combining the elements of the sequence using the given closure.

Beta
func remove(at: String.Index) -> Unicode.Scalar

Removes and returns the element at the specified position.

func removeAll(keepingCapacity: Bool = false)

Removes all elements from the collection.

func removeAll(where: (Unicode.Scalar) -> Bool)

Removes all the elements that satisfy the given predicate.

func removeFirst() -> Unicode.Scalar

Removes and returns the first element of the collection.

func removeFirst(Int)

Removes the specified number of elements from the beginning of the collection.

func removeLast() -> Unicode.Scalar

Removes and returns the last element of the collection.

func removeLast(Int)

Removes the specified number of elements from the end of the collection.

func removeSubrange(Range<String.Index>)

Removes the elements in the specified subrange from the collection.

func removeSubrange<R>(R)

Removes the elements in the specified subrange from the collection.

func replaceSubrange<C>(Range<String.UnicodeScalarView.Index>, with: C)

Replaces the elements within the specified bounds with the given Unicode scalar values.

func replaceSubrange<C, R>(R, with: C)

Replaces the specified subrange of elements with the given collection.

Beta
func reserveCapacity(Int)

Reserves enough space in the view’s underlying storage to store the specified number of ASCII characters.

func reversed() -> ReversedCollection<String.UnicodeScalarView>

Returns a view presenting the elements of the collection in reverse order.

func shuffled() -> [Unicode.Scalar]

Returns the elements of the sequence, shuffled.

func shuffled<T>(using: T) -> [Unicode.Scalar]

Returns the elements of the sequence, shuffled using the given generator as a source for randomness.

func sorted() -> [Unicode.Scalar]

Returns the elements of the sequence, sorted.

func sorted(by: (Unicode.Scalar, Unicode.Scalar) -> Bool) -> [Unicode.Scalar]

Returns the elements of the sequence, sorted using the given predicate as the comparison between elements.

func split(maxSplits: Int = Int.max, omittingEmptySubsequences: Bool = true, whereSeparator: (Unicode.Scalar) -> Bool) -> [Substring.UnicodeScalarView]

Returns the longest possible subsequences of the collection, in order, that don’t contain elements satisfying the given predicate.

func split(separator: Unicode.Scalar, maxSplits: Int = Int.max, omittingEmptySubsequences: Bool = true) -> [Substring.UnicodeScalarView]

Returns the longest possible subsequences of the collection, in order, around elements equal to the given element.

func starts<PossiblePrefix>(with: PossiblePrefix) -> Bool

Returns a Boolean value indicating whether the initial elements of the sequence are the same as the elements in another sequence.

func starts<PossiblePrefix>(with: PossiblePrefix, by: (Unicode.Scalar, PossiblePrefix.Element) -> Bool) -> Bool

Returns a Boolean value indicating whether the initial elements of the sequence are equivalent to the elements in another sequence, using the given predicate as the equivalence test.

func suffix(Int) -> Substring.UnicodeScalarView

Returns a subsequence, up to the given maximum length, containing the final elements of the collection.

func suffix(from: String.Index) -> Substring.UnicodeScalarView

Returns a subsequence from the specified position to the end of the collection.

Operator Functions

static func + <Other>(Other, String.UnicodeScalarView) -> String.UnicodeScalarView

Creates a new collection by concatenating the elements of a sequence and a collection.

static func + <Other>(String.UnicodeScalarView, Other) -> String.UnicodeScalarView

Creates a new collection by concatenating the elements of a collection and a sequence.

static func + <Other>(String.UnicodeScalarView, Other) -> String.UnicodeScalarView

Creates a new collection by concatenating the elements of two collections.

static func += <Other>(String.UnicodeScalarView, Other)

Appends the elements of a sequence to a range-replaceable collection.

Structures

struct String.UnicodeScalarView.Iterator

An iterator over the Unicode scalars that make up a UnicodeScalarView collection.

Relationships

From Protocol

See Also

Related String Types

struct Substring

A slice of a string.

protocol StringProtocol

A type that can represent a string as a collection of characters.

struct String.Index

A position of a character or code unit in a string.

struct String.UTF16View

A view of a string’s contents as a collection of UTF-16 code units.

struct String.UTF8View

A view of a string’s contents as a collection of UTF-8 code units.

Beta Software

This documentation contains preliminary information about an API or technology in development. This information is subject to change, and software implemented according to this documentation should be tested with final operating system software.

Learn more about using Apple's beta software