Structure

String.UnicodeScalarView

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

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 UnicodeScalar 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 values than its characters view.

let flag = "🇵🇷"
for c in flag.characters {
    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.index(where: { $0.value >= 128 }) {
    let asciiPrefix = String(favemoji.unicodeScalars.prefix(upTo: i))
    print(asciiPrefix)
}
// Prints "My favorite emoji is "

Nested Types

String.UnicodeScalarView.Iterator

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

String.UnicodeScalarView.Index

A position in a string’s UnicodeScalars view.

Symbols

Initializers

init()

Creates an empty view instance.

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 customPlaygroundQuickLook: PlaygroundQuickLookvar debugDescription: Stringvar description: 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: UnicodeScalar?

The first element of the collection.

var indices: DefaultBidirectionalIndices<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: UnicodeScalar?

The last element of the collection.

var lazy: LazyCollection<String.UnicodeScalarView>

A view onto this collection that provides lazy implementations of normally eager operations, such as map and filter.

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 lazy: LazyBidirectionalCollection<String.UnicodeScalarView>

A view onto this collection that provides lazy implementations of normally eager operations, such as map and filter.

var startIndex: String.UnicodeScalarView.Index

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

var underestimatedCount: Int

Returns a value less than or equal to the number of elements in the sequence, nondestructively.

var underestimatedCount: Int

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

Instance Methods

func append(UnicodeScalar)

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 contains(UnicodeScalar)

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

func contains(where: (UnicodeScalar) -> Bool)

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

func drop(while: (UnicodeScalar) -> Bool)

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

func dropFirst()

Returns a subsequence containing all but the first element of the sequence.

func dropFirst(Int)

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

func dropLast()

Returns a subsequence containing all but the last element of the sequence.

func dropLast(Int)

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

func elementsEqual<OtherSequence>(OtherSequence)

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

func elementsEqual<OtherSequence>(OtherSequence, by: (UnicodeScalar, UnicodeScalar) -> Bool)

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

func enumerated()

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((UnicodeScalar) -> Bool)

Returns an array containing, in order, the elements of the sequence that satisfy the given predicate.

func first(where: (UnicodeScalar) -> Bool)

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

func flatMap<SegmentOfResult>((UnicodeScalar) -> SegmentOfResult)

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

func flatMap<ElementOfResult>((UnicodeScalar) -> ElementOfResult?)

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

func forEach((UnicodeScalar) -> Void)

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

func index(after: String.UnicodeScalarView.Index)

Returns the next consecutive location after i.

func index(before: String.UnicodeScalarView.Index)

Returns the previous consecutive location before i.

func index(of: UnicodeScalar)

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

func index(where: (UnicodeScalar) -> Bool)

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

func lexicographicallyPrecedes<OtherSequence>(OtherSequence)

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: (UnicodeScalar, UnicodeScalar) -> 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()

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

func map<T>((UnicodeScalar) -> T)

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

func map<T>((UnicodeScalar) -> T)

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

func max()

Returns the maximum element in the sequence.

func max(by: (UnicodeScalar, UnicodeScalar) -> Bool)

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

func min()

Returns the minimum element in the sequence.

func min(by: (UnicodeScalar, UnicodeScalar) -> Bool)

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

func popFirst()

Removes and returns the first element of the collection.

func popLast()

Removes and returns the last element of the collection.

func prefix(Int)

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

func prefix(through: String.UnicodeScalarView.Index)

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

func prefix(upTo: String.UnicodeScalarView.Index)

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

func prefix(while: (UnicodeScalar) -> Bool)

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

func reduce<Result>(Result, (Result, UnicodeScalar) -> Result)

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

func removeFirst()

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()

Removes and returns the last element of the collection.

func removeLast(Int)

Removes the given number of elements from the end of 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 reserveCapacity(Int)

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

func reversed()

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

func sorted()

Returns the elements of the sequence, sorted.

func sorted(by: (UnicodeScalar, UnicodeScalar) -> Bool)

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

func split(maxSplits: Int, omittingEmptySubsequences: Bool, whereSeparator: (UnicodeScalar) -> Bool)

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

func split(separator: UnicodeScalar, maxSplits: Int, omittingEmptySubsequences: Bool)

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

func starts<PossiblePrefix>(with: PossiblePrefix)

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: (UnicodeScalar, UnicodeScalar) -> 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)

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

func suffix(from: String.UnicodeScalarView.Index)

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

Subscripts

subscript(String.UnicodeScalarView.Index)

Accesses the Unicode scalar value at the given position.

subscript(Range<String.UnicodeScalarView.Index>)

Accesses the Unicode scalar values in the given range.