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Peter71
Peter71

Reputation: 2300

Swift: reference to array element by key

I have written my own small function to find an element in an array using a key. But I'm sure there is a ready to use implementation in Swift to get it in one line. Any hint?

func objectAtKey(array: [T], key: String) -> T? {
    for element in array {
        if element.name == key {
            return element
        }
    }
    return nil
}

I also know function indexOf, but this return an index, I have to use for further access. I think this is slower:

let index = array.indexOf({$0.name == key})

Upvotes: 1

Views: 1360

Answers (3)

Martin R
Martin R

Reputation: 539705

In Swift 3 (Xcode 8, currently beta 6) you can do

if let el = array.first(where: { $0.name == key }) {
    // `el` is the first array element satisfying the condition.
    // ...
} else {
    // No array element satisfies the condition.
}

using the first(where:) method of the Sequence protocol:

/// Returns the first element of the sequence that satisfies the given
/// predicate or nil if no such element is found.
///
/// - Parameter 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.
/// - Returns: The first match or `nil` if there was no match.
public func first(where predicate: (Element) throws -> Bool) rethrows -> Element?

Upvotes: 4

Rashwan L
Rashwan L

Reputation: 38833

I think the best solution for you here is to use the indexOf with a Predicate that you have written. I would have written it like this though:

let array = ["Foo", "Bar", "Test"]
if let i = array.indexOf({$0 == "Foo"}) {
     print(array[i])
}

To handle if the value does not exists if you need that.

Upvotes: 1

Marco Santarossa
Marco Santarossa

Reputation: 4066

Try this:

let element = array.filter{ $0.name == key }.first

Upvotes: 0

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