I might have an array that looks like the following:
[1, 4, 2, 2, 6, 24, 15, 2, 60, 15, 6]
Or, reall
Slightly more succinct syntax version of Daniel Krom's Swift 2 answer, using a trailing closure and shorthand argument name, which appears to be based on Airspeed Velocity's original answer:
func uniq(source: S) -> [E] {
var seen = [E: Bool]()
return source.filter { seen.updateValue(true, forKey: $0) == nil }
}
Example of implementing a custom type that can be used with uniq(_:)
(which must conform to Hashable
, and thus Equatable
, because Hashable
extends Equatable
):
func ==(lhs: SomeCustomType, rhs: SomeCustomType) -> Bool {
return lhs.id == rhs.id // && lhs.someOtherEquatableProperty == rhs.someOtherEquatableProperty
}
struct SomeCustomType {
let id: Int
// ...
}
extension SomeCustomType: Hashable {
var hashValue: Int {
return id
}
}
In the above code...
id
, as used in the overload of ==
, could be any Equatable
type (or method that returns an Equatable
type, e.g., someMethodThatReturnsAnEquatableType()
). The commented-out code demonstrates extending the check for equality, where someOtherEquatableProperty
is another property of an Equatable
type (but could also be a method that returns an Equatable
type).
id
, as used in the hashValue
computed property (required to conform to Hashable
), could be any Hashable
(and thus Equatable
) property (or method that returns a Hashable
type).
Example of using uniq(_:)
:
var someCustomTypes = [SomeCustomType(id: 1), SomeCustomType(id: 2), SomeCustomType(id: 3), SomeCustomType(id: 1)]
print(someCustomTypes.count) // 4
someCustomTypes = uniq(someCustomTypes)
print(someCustomTypes.count) // 3