---
title: span
framework: swift
role: symbol
role_heading: Instance Property
path: swift/substring/utf8view/span
---

# span

A span over the UTF8 code units that make up this substring.

## Declaration

```swift
var span: Span<UTF8.CodeUnit> { get }
```

## Discussion

Discussion note: In the case of bridged UTF16 String instances (on Apple platforms,) this property needs to transcode the code units every time it is called. For example, if string has the bridged UTF16 representation, for word in string.split(separator: “ “) { useSpan(word.span) } is accidentally quadratic because of this issue. A workaround is to explicitly convert the string into its native UTF8 representation: var nativeString = consume string nativeString.makeContiguousUTF8() for word in nativeString.split(separator: “ “) { useSpan(word.span) } This second option has linear time complexity, as expected. Returns: a Span over the UTF8 code units of this Substring. Complexity: O(1) for native UTF8 Strings, O(n) for bridged UTF16 Strings.