---
title: "subscript(_:default:)"
framework: swift
role: symbol
role_heading: Instance Subscript
path: "swift/dictionary/subscript(_:default:)"
---

# subscript(_:default:)

Accesses the value with the given key, falling back to the given default value if the key isn’t found.

## Declaration

```swift
subscript(key: Key, default defaultValue: @autoclosure () -> Value) -> Value { get set }
```

## Parameters

- `key`: The key the look up in the dictionary.
- `defaultValue`: The default value to use if key doesn’t exist in the dictionary.

## Return Value

Return Value The value associated with key in the dictionary; otherwise, defaultValue.

## Overview

Overview Use this subscript when you want either the value for a particular key or, when that key is not present in the dictionary, a default value. This example uses the subscript with a message to use in case an HTTP response code isn’t recognized: var responseMessages = [200: "OK",                         403: "Access forbidden",                         404: "File not found",                         500: "Internal server error"]

let httpResponseCodes = [200, 403, 301] for code in httpResponseCodes {     let message = responseMessages[code, default: "Unknown response"]     print("Response \(code): \(message)") } // Prints "Response 200: OK" // Prints "Response 403: Access forbidden" // Prints "Response 301: Unknown response" When a dictionary’s Value type has value semantics, you can use this subscript to perform in-place operations on values in the dictionary. The following example uses this subscript while counting the occurrences of each letter in a string: let message = "Hello, Elle!" var letterCounts: [Character: Int] = [:] for letter in message {     letterCounts[letter, default: 0] += 1 } // letterCounts == ["H": 1, "e": 2, "l": 4, "o": 1, ...] When letterCounts[letter, default: 0] += 1 is executed with a value of letter that isn’t already a key in letterCounts, the specified default value (0) is returned from the subscript, incremented, and then added to the dictionary under that key. note: Do not use this subscript to modify dictionary values if the dictionary’s Value type is a class. In that case, the default value and key are not written back to the dictionary after an operation.

## See Also

### Accessing Keys and Values

- [subscript(_:)](swift/dictionary/subscript(_:)-8rfql.md)
- [index(forKey:)](swift/dictionary/index(forkey:).md)
- [subscript(_:)](swift/dictionary/subscript(_:)-4bhoo.md)
- [keys](swift/dictionary/keys-swift.property.md)
- [values](swift/dictionary/values-swift.property.md)
- [first](swift/dictionary/first.md)
- [randomElement()](swift/dictionary/randomelement().md)
- [randomElement(using:)](swift/dictionary/randomelement(using:).md)