---
title: queryItems
framework: foundation
role: symbol
role_heading: Instance Property
path: foundation/nsurlcomponents/queryitems
---

# queryItems

The query URL component as an array of name/value pairs.

## Declaration

```swift
var queryItems: [URLQueryItem]? { get set }
```

## Discussion

Discussion When you get this property’s value, the NSURLComponents class parses the query string and returns an array of NSURLQueryItem objects, each of which represents a single key-value pair, in the order in which they appear in the original query string. Because a name may appear more than once in a single query string, the name properties of query items are not guaranteed to be unique. If the query property is an empty string, the queryItems property is an empty array. If the query property is nil, the queryItems property is also nil. When you set this property’s value, the NSURLComponents class joins each name/value pair with a = delimiter and joins the array with a & delimiter, then sets the query property to the resulting string. Setting the queryItems property to an empty array sets the query property to an empty string, and setting the queryItems property to nil sets the query property to nil. note: RFC 3986 specifies which characters must be percent-encoded in the query component of a URL, but not how those characters should be interpreted. The use of delimited key-value pairs is a common convention, but isn’t standardized by a specification. Therefore, you may encounter interoperability problems with other implementations that follow this convention. One notable example of potential interoperability problems is how the plus sign (+) character is handled: According to RFC 3986, the plus sign is a valid character within a query, and doesn’t need to be percent-encoded. However, according to the W3C recommendations for URI addressing, the plus sign is reserved as shorthand notation for a space within a query string (for example, ?greeting=hello+world). If a URL query component contains a date formatted according to RFC 3339 with a plus sign in the timezone offset (for example, 2013-12-31T14:00:00+00:00), interpreting the plus sign as a space results in an invalid time format. RFC 3339 specifies how dates should be formatted, but doesn’t advise whether the plus sign must be percent-encoded in a URL. Depending on the implementation receiving this URL, you may need to preemptively percent-encode the plus sign character. As an alternative, consider encoding complex and/or potentially problematic data in a more robust data-interchange format, such as JSON or XML. To ensure you can compose and decompose URL queries even with empty components, the NSURLComponents class has the following behavior for cases where no name or value is present: If a name-value pair has nothing before its equals sign, the name property of the corresponding query item is a zero-length string. If a name-value pair has nothing after its equals sign, the value property of the corresponding query item is a zero-length string. If a name-value pair has no equals sign, the value property of the corresponding query item is nil. If a name-value pair is empty (that is, the query string starts with &, ends with &, or contains &``&), the corresponding query item has a zero-length name and nil value. For example, in the URL http://www.example.com/index.php?key1=value1&key2=value2, this property’s value is an array of two NSURLQueryItem objects: one whose name property is key1 and whose value property is value1, and one whose name property is key2 and whose value property is value2.

## See Also

### Accessing components in native format

- [fragment](foundation/nsurlcomponents/fragment.md)
- [host](foundation/nsurlcomponents/host.md)
- [encodedHost](foundation/nsurlcomponents/encodedhost.md)
- [password](foundation/nsurlcomponents/password.md)
- [path](foundation/nsurlcomponents/path.md)
- [port](foundation/nsurlcomponents/port.md)
- [query](foundation/nsurlcomponents/query.md)
- [scheme](foundation/nsurlcomponents/scheme.md)
- [user](foundation/nsurlcomponents/user.md)