Returns a Boolean value indicating whether the sequence contains an element that satisfies the given predicate.
SDK
- Xcode 8.0+
Framework
- Swift Standard Library
Declaration
Parameters
predicateA closure that takes an element of the sequence as its argument and returns a Boolean value that indicates whether the passed element represents a match.
Return Value
true if the sequence contains an element that satisfies predicate; otherwise, false.
Discussion
You can use the predicate to check for an element of a type that doesn’t conform to the Equatable protocol, such as the HTTPResponse enumeration in this example.
enum HTTPResponse {
case ok
case error(Int)
}
let lastThreeResponses: [HTTPResponse] = [.ok, .ok, .error(404)]
let hadError = lastThreeResponses.contains { element in
if case .error = element {
return true
} else {
return false
}
}
// 'hadError' == true
Alternatively, a predicate can be satisfied by a range of Equatable elements or a general condition. This example shows how you can check an array for an expense greater than $100.
let expenses = [21.37, 55.21, 9.32, 10.18, 388.77, 11.41]
let hasBigPurchase = expenses.contains { $0 > 100 }
// 'hasBigPurchase' == true
Complexity: O(n), where n is the length of the sequence.