Instance MethodSwift

min(by:)

Returns the minimum element in the sequence, using the given predicate as the comparison between elements.

• Available because `Self` conforms to `Sequence`.

``@warn_unqualified_access func min(by areInIncreasingOrder: (Self.Element, Self.Element) throws -> Bool) rethrows -> Self.Element?``

Parameters

areInIncreasingOrder

A predicate that returns `true` if its first argument should be ordered before its second argument; otherwise, `false`.

Returns

The sequenceâ€™s minimum element, according to `areInIncreasingOrder`. If the sequence has no elements, returns `nil`.

Overview

The predicate must be a strict weak ordering over the elements. That is, for any elements `a`, `b`, and `c`, the following conditions must hold:

• `areInIncreasingOrder(a, a)` is always `false`. (Irreflexivity)

• If `areInIncreasingOrder(a, b)` and `areInIncreasingOrder(b, c)` are both `true`, then `areInIncreasingOrder(a, c)` is also `true`. (Transitive comparability)

• Two elements are incomparable if neither is ordered before the other according to the predicate. If `a` and `b` are incomparable, and `b` and `c` are incomparable, then `a` and `c` are also incomparable. (Transitive incomparability)

This example shows how to use the `min(by:)` method on a dictionary to find the key-value pair with the lowest value.

``````let hues = ["Heliotrope": 296, "Coral": 16, "Aquamarine": 156]
let leastHue = hues.min { a, b in a.value < b.value }
print(leastHue)
// Prints "Optional((key: "Coral", value: 16))"``````