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Alex Rupérez

Published: 23 Jan 10:18
I starred BalestraPatrick/Stryng at GitHub.
Swift strings taken to a whole new syntax level.
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Circle CI Carthage License Platform Twitter: @BalestraPatrick


Stryng is designed to make it easier to work with strings by using the common and easy to remember subscript syntax and accessing characters and ranges with Int indices.

Swift's strings management is one of the most painful feature of the language. Sure, it's great to have Unicode correctness and efficiency, but this comes at a cost: too much verbosity and complexity.


Retrieve a single character at a specific position.

let string = "Example"
// With Stryng
string[1] // "x"
// Without
string[string.index(string.startIndex, offsetBy: 1)] // "x"

Retrieve the substring up to a specific index.

let string = "Example"
// With Stryng
string[..<2] // "Ex"
// Without
string[..<string.index(string.startIndex, offsetBy: 2)] // "Ex"

Retrieve the substring between two indices.

let string = "Example"
// With Stryng
string[1..<6] // "xampl"
// Without
string[string.index(string.startIndex, offsetBy: 1)..<string.index(string.startIndex, offsetBy: 6)] // "Ex"

Retrieve positions of a all substring occurences.

let string = "Example Example"
let occurences = string["xa"] // Returns a [Range<String.Index>] containing all positions of the subtring.

Convert a Substring to a String.

let example = "Example"
example[1...5].string // Returns a `String?` instead of a `Substring?`


This is an up to date list of the supported subscripts. Take a look at StryngTests.swift if you want to see some more real code examples.

// String[1]
public subscript(index: Int) -> Character?

// String[0..<1]
public subscript(range: Range<Int>) -> Substring?

// String[0...1]
public subscript(range: ClosedRange<Int>) -> Substring?

// String[..<1]
public subscript(value: PartialRangeUpTo<Int>) -> Substring?

// String[...1]
public subscript(value: PartialRangeThrough<Int>) -> Substring?

// String[1...]
public subscript(value: PartialRangeFrom<Int>) -> Substring?

// String["substring"]
public subscript(string: String) -> [Range<String.Index>]

// String["begin"..."end"]
public subscript(range: ClosedRange<String>) -> [ClosedRange<String.Index>]

// String["begin"..<"end"]
public subscript(range: Range<String>) -> [Range<String.Index>]

// String[Character("a")]
public subscript(character: Character) -> [String.Index]

// String["begin"...]
public subscript(range: PartialRangeFrom<String>) -> PartialRangeFrom<String.Index>?

// String[..."end"]
public subscript(range: PartialRangeThrough<String>) -> PartialRangeThrough<String.Index>?



To install via Cocoapods, add the following line to your Podfile:

pod 'Stryng'

Swift Package Manager

To install via the Swift Package Manager, add the following line to the dependencies array in your Package.swift file:

.package(url: "", from: "0.4.1")

Then, still in your Package.swift, add "Stryng" to your target's dependencies array.

Finally, in your terminal, run the following command to update your dependencies:

$ swift package update


Yes, string traversal in Swift can be slow. The reason why these subscripts don't exist in the standard library is that some people think that it hides the performance implications of traversing a string. Traversing a string from the startIndex until the endIndex has complexity O(n). If you need to get a character at a specific index, in one way or another you will have to traverse the string, but why would you need 3 lines of code instead of 1 to do that if you know what you're doing?

This is why Stryng is here to help you.


We'd love your help. Head over to the issues with your feedback. Bonus points if you open a Pull request with a failing test for a bug or a new feature! ⭐️


I'm Patrick Balestra.


Twitter: @BalestraPatrick.


Stryng is available under the MIT license. See the LICENSE file for more info.