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:
Because sets don’t have any concept of ordering, they don’t have an
append() method. Instead, they use
insert(), like this:
Available from iOS – learn more in my book Pro Swift
Did this solution work for you? Please pass it on!
Other people are reading…
About the Swift Knowledge Base
This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.
Upgrade to the premium experience
Get all 40 projects in PDF and ePub, plus exclusive content that will take your Swift learning to the next level – buy the Hacking with Swift book today!