---
title: KeyValuePairs
framework: swift
role: symbol
role_heading: Structure
path: swift/keyvaluepairs
---

# KeyValuePairs

A lightweight collection of key-value pairs.

## Declaration

```swift
@frozen struct KeyValuePairs<Key, Value>
```

## Overview

Overview Use a KeyValuePairs instance when you need an ordered collection of key-value pairs and don’t require the fast key lookup that the Dictionary type provides. Unlike key-value pairs in a true dictionary, neither the key nor the value of a KeyValuePairs instance must conform to the Hashable protocol. You initialize a KeyValuePairs instance using a Swift dictionary literal. Besides maintaining the order of the original dictionary literal, KeyValuePairs also allows duplicates keys. For example: let recordTimes: KeyValuePairs = ["Florence Griffith-Joyner": 10.49,                                       "Evelyn Ashford": 10.76,                                       "Evelyn Ashford": 10.79,                                       "Marlies Gohr": 10.81] print(recordTimes.first!) // Prints "(key: "Florence Griffith-Joyner", value: 10.49)" Some operations that are efficient on a dictionary are slower when using KeyValuePairs. In particular, to find the value matching a key, you must search through every element of the collection. The call to firstIndex(where:) in the following example must traverse the whole collection to find the element that matches the predicate: let runner = "Marlies Gohr" if let index = recordTimes.firstIndex(where: { $0.0 == runner }) {     let time = recordTimes[index].1     print("\(runner) set a 100m record of \(time) seconds.") } else {     print("\(runner) couldn't be found in the records.") } // Prints "Marlies Gohr set a 100m record of 10.81 seconds." Key-Value Pairs as a Function Parameter When calling a function with a KeyValuePairs parameter, you can pass a Swift dictionary literal without causing a Dictionary to be created. This capability can be especially important when the order of elements in the literal is significant. For example, you could create an IntPairs structure that holds a list of two-integer tuples and use an initializer that accepts a KeyValuePairs instance. struct IntPairs {     var elements: [(Int, Int)]

init(_ elements: KeyValuePairs<Int, Int>) {         self.elements = Array(elements)     } } When you’re ready to create a new IntPairs instance, use a dictionary literal as the parameter to the IntPairs initializer. The KeyValuePairs instance preserves the order of the elements as passed. let pairs = IntPairs([1: 2, 1: 1, 3: 4, 2: 1]) print(pairs.elements) // Prints "[(1, 2), (1, 1), (3, 4), (2, 1)]"

## Topics

### Initializers

- [init(dictionaryLiteral:)](swift/keyvaluepairs/init(dictionaryliteral:).md)

### Instance Properties

- [span](swift/keyvaluepairs/span.md)

### Default Implementations

- [BidirectionalCollection Implementations](swift/keyvaluepairs/bidirectionalcollection-implementations.md)
- [Collection Implementations](swift/keyvaluepairs/collection-implementations.md)
- [CustomDebugStringConvertible Implementations](swift/keyvaluepairs/customdebugstringconvertible-implementations.md)
- [CustomStringConvertible Implementations](swift/keyvaluepairs/customstringconvertible-implementations.md)
- [RandomAccessCollection Implementations](swift/keyvaluepairs/randomaccesscollection-implementations.md)
- [Sequence Implementations](swift/keyvaluepairs/sequence-implementations.md)

## Relationships

### Conforms To

- [BidirectionalCollection](swift/bidirectionalcollection.md)
- [Collection](swift/collection.md)
- [Copyable](swift/copyable.md)
- [CustomDebugStringConvertible](swift/customdebugstringconvertible.md)
- [CustomStringConvertible](swift/customstringconvertible.md)
- [Escapable](swift/escapable.md)
- [ExpressibleByDictionaryLiteral](swift/expressiblebydictionaryliteral.md)
- [RandomAccessCollection](swift/randomaccesscollection.md)
- [Sendable](swift/sendable.md)
- [SendableMetatype](swift/sendablemetatype.md)
- [Sequence](swift/sequence.md)

## See Also

### Special-Use Collections

- [repeatElement(_:count:)](swift/repeatelement(_:count:).md)
- [CollectionOfOne](swift/collectionofone.md)
- [EmptyCollection](swift/emptycollection.md)
- [DictionaryLiteral](swift/dictionaryliteral.md)