Common APIs — prefix/suffix/contains, split/join
Use practical String APIs: hasPrefix/hasSuffix/contains, split into parts, and join arrays back with separators.
Common APIs — prefix/suffix/contains, split/join is a free Swift Academy lesson on CoddyKit — lesson 2 of 3. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Swift Academy learning path, one of 3 lessons in the course, and your progress syncs across the web and the CoddyKit app.
Overview
Swift offers handy String helpers for everyday tasks: hasPrefix, hasSuffix, contains, split, and joined. You'll combine them safely on small screens.
Prefix/Suffix/Contains
Check beginnings, endings, or substring presence with hasPrefix, hasSuffix, and contains.
let path = "/usr/local/bin"
print(path.hasPrefix("/usr")) // true
print(path.hasSuffix("bin")) // true
print(path.contains("local")) // trueCase-insensitive search
APIs are case-sensitive. For a simple case-insensitive check, compare lowercased() (or uppercased()).
let note = "Welcome to Swift"
let found = note.lowercased().contains("swift".lowercased())
print(found) // trueSplit into parts
split(separator:) returns Substrings (views). Convert to String if you will store them long-term.
let csv = "Ada,Bob,Charlie"
let parts = csv.split(separator: ",") // [Substring]
print(parts) // ["Ada","Bob","Charlie"]
print(parts.first ?? "")Split variants
Control empty pieces via omittingEmptySubsequences, or split by a rule using whereSeparator.
let path = "///usr//local/bin"
let pieces1 = path.split(separator: "/", omittingEmptySubsequences: true)
let pieces2 = path.split(separator: "/", omittingEmptySubsequences: false)
print(pieces1) // skips empties
print(pieces2) // keeps empties
let vowels = "aeiou"
let tokens = "hello world".split(whereSeparator: { vowels.contains($0) })
print(tokens)Join parts
Use joined(separator:) on arrays to build a single string with a chosen separator.
let words: [String] = ["one","two","three"]
let hyphen = words.joined(separator: "-")
print(hyphen) // one-two-threeJoin method
Quick check: Which method joins an array of strings with a separator?
Recap
Recap: Detect text with hasPrefix/hasSuffix/contains. Split with split (fine-tune empties/rules). Rebuild strings using joined.
Frequently asked questions
Is the “Common APIs — prefix/suffix/contains, split/join” lesson free?
Yes — the full text of “Common APIs — prefix/suffix/contains, split/join” is free to read here on the web, and the Swift Academy course includes 3 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Swift Academy course, upgrade to CoddyKit PRO.
What will I learn in “Common APIs — prefix/suffix/contains, split/join”?
Use practical String APIs: hasPrefix/hasSuffix/contains, split into parts, and join arrays back with separators. You practise Swift Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Swift Academy?
No prior experience is required. Swift Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 2 of 3, so you can start here or from the beginning and move at your own pace.
How long does the “Common APIs — prefix/suffix/contains, split/join” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Swift Academy lesson?
Yes. Every Swift Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- Strings & Unicode — graphemes, indices, substrings, APIs
- Common APIs — prefix/suffix/contains, split/join
- Performance notes — copy-on-write