Swift Substring to String | Swift Substring | Swift Quick Tips 

Swift Programming

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A Substring is a portion of a String, and Swift Substring provides a convenient way to manipulate and extract these smaller segments. Within this article, we will explore Substrings and how to convert Substrings to Strings. 

Related topics in series:

What is a Substring in Swift?

Swift has its own dedicated type, that holds a smaller portions of strings. For instance, imagine you had the String “Apple”, and you just wanted a part of it e.g. “App”. The smaller portion “App” is a Substring. In Swift, a substring is like a smaller piece of a bigger word or sentence that you can work with.

Why use Substrings

Substrings are handy because they let you work with just a part of a word or sentence without making a whole new copy of it. 

How Substrings work

Swift Strings are value types, meaning that if you use one String to make a new one, then it is copied over. Whereas, a Substring, on the other hand, is a reference back to the original String from which it came. 

A substring can reuse part of the memory that’s used to store the original string, or part of the memory that’s used to store another substring…. substrings aren’t suitable for long-term storage — because they reuse the storage of the original string, the entire original string must be kept in memory as long as any of its substrings are being used.

Swift Documentation

Creating a Substring

In the example belo, you can utilise the prefix method to return a subsequence from the start of a collection to the specified position:

Converting a Substring to a String

Converting a Swift Substring to a String is extremely straight forward, you can use the String initialiser.


Substrings in Swift are smaller pieces of a larger text. They are value types, which means they are independent of the original text and can be used for efficient manipulation without altering the original string.