Return Value 戻り値
The first element of the sequence that satisfies predicate
, or nil
if there is no element that satisfies predicate
.
predicate
満たすシーケンスの最初の要素、またはpredicate
を満たす要素が無いならばnil
。
Availability 有効性
Technology
func first(where predicate: (Self.Element) throws -> Bool
) rethrows -> Self.Element?
The first element of the sequence that satisfies predicate
, or nil
if there is no element that satisfies predicate
.
predicate
満たすシーケンスの最初の要素、またはpredicate
を満たす要素が無いならばnil
。
predicate
A closure that takes an element of the sequence as its argument and returns a Boolean value indicating whether the element is a match. あるクロージャ、それは1つの要素をそれの引数として取り、その要素が合致するものかどうかを指し示しているブール値を返します。
The following example uses the first(where:)
method to find the first negative number in an array of integers:
以下の例は、first(where:)
メソッドを使って、整数の配列において最初の負数を見つけます:
let numbers = [3, 7, 4, -2, 9, -6, 10, 1]
if let firstNegative = numbers.first(where: { $0 < 0 }) {
print("The first negative number is \(firstNegative).")
}
// Prints "The first negative number is -2."
Complexity
O(n), where n is the length of the sequence.