What are sets?
Swift version: 5.2
Sets are a type of sequence similar to arrays, except they may not store any item more than once and are unordered. This eliminates them from many places where you would use an array, but they do have one special super-power: it’s extremely fast to check whether a set contains a specific value. In fact, sets perform this operation at the same speed whether they contain 10 items or 10,000 items.
Sets can be created directly from arrays, then used like them in many ways. For example:
var numbers = Set([1, 2, 3])You can then go ahead and check whether that contains a specific value, like this:
print(numbers.contains(5))Because sets don’t have any concept of ordering, they don’t have an append() method. Instead, they use insert(), like this:
numbers.insert(5)
SPONSORED ViRE offers discoverable way of working with regex. It provides really readable regex experience, code complete & cheat sheet, unit tests, powerful replace system, step-by-step search & replace, regex visual scheme, regex history & playground. ViRE is available on Mac & iPad.
Sponsor Hacking with Swift and reach the world's largest Swift community!
Available from iOS – learn more in my book Pro Swift
Similar solutions…
- When to use a set rather than an array
- How to add a shadow to a UIView
- What is the @GestureState property wrapper?
- What are convenience initializers?
- How to let users move rows in a list
About the Swift Knowledge Base
This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.
