# UTF8Span A borrowed view into contiguous memory that contains validly-encoded UTF-8 code units. ``` @frozen struct UTF8Span ``` ## Topics ### Structures [`struct CharacterIterator`](/documentation/Swift/UTF8Span/CharacterIterator) Iterate the `Character` contents of a `UTF8Span`. [`struct UnicodeScalarIterator`](/documentation/Swift/UTF8Span/UnicodeScalarIterator) Iterate the `Unicode.Scalar`s contents of a `UTF8Span`. ### Initializers [`init(unchecked: Span, isKnownASCII: Bool)`](/documentation/Swift/UTF8Span/init(unchecked:isKnownASCII:)) Creates a UTF8Span, bypassing safety and security checks. The caller must guarantee that `codeUnits` contains validly-encoded UTF-8, or else undefined behavior may result upon use. If `isKnownASCII: true is passed`, the contents must be ASCII, or else undefined behavior may result upon use. [`init(validating: consuming Span) throws(UTF8.ValidationError)`](/documentation/Swift/UTF8Span/init(validating:)) Creates a UTF8Span containing `codeUnits`. Validates that the input is valid UTF-8, otherwise throws an error. ### Instance Properties [`var count: Int`](/documentation/Swift/UTF8Span/count) The number of UTF-8 code units in the span. [`var isEmpty: Bool`](/documentation/Swift/UTF8Span/isEmpty) A Boolean value that indicates whether the UTF-8 span is empty. [`var isKnownASCII: Bool`](/documentation/Swift/UTF8Span/isKnownASCII) Returns whether contents are known to be all-ASCII. A return value of `true` means that all code units are ASCII. A return value of `false` means there *may* be non-ASCII content. [`var isKnownNFC: Bool`](/documentation/Swift/UTF8Span/isKnownNFC) Returns whether the contents are known to be NFC. This is not always checked at initialization time and is set by `checkForNFC`. [`var span: Span`](/documentation/Swift/UTF8Span/span) A span used to access the code units. ### Instance Methods [`func bytesEqual(to: some Sequence) -> Bool`](/documentation/Swift/UTF8Span/bytesEqual(to:)) Whether this span has the same bytes as `other`. [`func charactersEqual(to: some Sequence) -> Bool`](/documentation/Swift/UTF8Span/charactersEqual(to:)) Whether this span has the same `Character`s as `other`. [`func checkForASCII() -> Bool`](/documentation/Swift/UTF8Span/checkForASCII()) Do a scan checking for whether the contents are all-ASCII. [`func checkForNFC(quickCheck: Bool) -> Bool`](/documentation/Swift/UTF8Span/checkForNFC(quickCheck:)) Do a scan checking for whether the contents are in Normal Form C. When the contents are in NFC, canonical equivalence checks are much faster. [`func isCanonicallyEquivalent(to: UTF8Span) -> Bool`](/documentation/Swift/UTF8Span/isCanonicallyEquivalent(to:)) Whether `self` is equivalent to `other` under Unicode Canonical Equivalence. [`func isCanonicallyLessThan(UTF8Span) -> Bool`](/documentation/Swift/UTF8Span/isCanonicallyLessThan(_:)) Whether `self` orders less than `other` under Unicode Canonical Equivalence using normalized code-unit order (in NFC). [`func isTriviallyIdentical(to: UTF8Span) -> Bool`](/documentation/Swift/UTF8Span/isTriviallyIdentical(to:)) Returns a Boolean value indicating whether two instances refer to the same memory region, and have the same flags (such as [`isKnownASCII`](/documentation/Swift/UTF8Span/isKnownASCII)). [`func makeCharacterIterator() -> UTF8Span.CharacterIterator`](/documentation/Swift/UTF8Span/makeCharacterIterator()) Returns an iterator that will construct `Character`s from the underlying UTF-8 content. [`func makeUnicodeScalarIterator() -> UTF8Span.UnicodeScalarIterator`](/documentation/Swift/UTF8Span/makeUnicodeScalarIterator()) Returns an iterator that will decode the code units into `Unicode.Scalar`s. [`func unicodeScalarsEqual(to: some Sequence) -> Bool`](/documentation/Swift/UTF8Span/unicodeScalarsEqual(to:)) Whether this span has the same `Unicode.Scalar`s as `other`. ## Relationships ### Conforms To [`ContiguousBytes`](/documentation/Foundation/ContiguousBytes) [`BitwiseCopyable`](/documentation/Swift/BitwiseCopyable) --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)