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. This is lesson 2 of 3. Any 3 lessons of this learning path are free to read in full — after that, CoddyKit PRO unlocks every lesson, plus hands-on practice with a built-in code editor and a 24/7 AI tutor. It is part of the Swift Academy learning path, and your progress syncs across the web and the CoddyKit app. The Swift Academy course includes 3 lessons in total.
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.
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Frequently Asked Questions
Is the “Common APIs — prefix/suffix/contains, split/join” lesson free?
Yes — any 3 lessons of the Swift Academy learning path, including “Common APIs — prefix/suffix/contains, split/join”, are free to read in full here on the web. After that, CoddyKit PRO unlocks every lesson, plus interactive practice with a built-in code editor and a 24/7 AI tutor. The Swift Academy course includes 3 lessons in total.
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, so you can start here or from the beginning and move at your own pace. This is lesson 2 of 3.
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