Swift Language Arrays Sorting an Array
Example
var array = [3, 2, 1]
Creating a new sorted array
As Array conforms to SequenceType, we can generate a new array of the sorted elements using a built in sort method.
2.12.2
In Swift 2, this is done with the sort() method.
let sorted = array.sort() // [1, 2, 3]
3.0
As of Swift 3, it has been re-named to sorted().
let sorted = array.sorted() // [1, 2, 3]
Sorting an existing array in place
As Array conforms to MutableCollectionType, we can sort its elements in place.
2.12.2
In Swift 2, this is done using the sortInPlace() method.
array.sortInPlace() // [1, 2, 3]
3.0
As of Swift 3, it has been renamed to sort().
array.sort() // [1, 2, 3]
Note: In order to use the above methods, the elements must conform to the
Comparableprotocol.
Sorting an array with a custom ordering
You may also sort an array using a closure to define whether one element should be ordered before another – which isn't restricted to arrays where the elements must be Comparable. For example, it doesn't make sense for a Landmark to be Comparable – but you can still sort an array of landmarks by height or name.
struct Landmark {
let name : String
let metersTall : Int
}
var landmarks = [Landmark(name: "Empire State Building", metersTall: 443),
Landmark(name: "Eifell Tower", metersTall: 300),
Landmark(name: "The Shard", metersTall: 310)]
2.12.2
// sort landmarks by height (ascending)
landmarks.sortInPlace {$0.metersTall < $1.metersTall}
print(landmarks) // [Landmark(name: "Eifell Tower", metersTall: 300), Landmark(name: "The Shard", metersTall: 310), Landmark(name: "Empire State Building", metersTall: 443)]
// create new array of landmarks sorted by name
let alphabeticalLandmarks = landmarks.sort {$0.name < $1.name}
print(alphabeticalLandmarks) // [Landmark(name: "Eifell Tower", metersTall: 300), Landmark(name: "Empire State Building", metersTall: 443), Landmark(name: "The Shard", metersTall: 310)]
3.0
// sort landmarks by height (ascending)
landmarks.sort {$0.metersTall < $1.metersTall}
// create new array of landmarks sorted by name
let alphabeticalLandmarks = landmarks.sorted {$0.name < $1.name}
Note: String comparison can yield unexpected results if the strings are inconsistent, see Sorting an Array of Strings.
