Note
The following sections show different ways of performing the same tasks. They say nothing about which version is better.
The
filter
method
looks like this:
func filter(_ isIncluded: (Element) throws -> Bool) rethrows -> [Element]
It is
a simple method on
Sequence,
and we have already used it. The input function takes an element of the sequence and returns either
false
or
true
.
filter
returns an array of only those elements for which the input function returns
true
:
let numbers = [-4,4,2,-8,0] let negative = numbers.filter {$0<0} // [-4, -8]
Set
and
Dictionary
have their own versions of this method, which return a Set or Dictionary respectively.