# queryItems The query URL component as an array of name/value pairs. ``` var queryItems: [URLQueryItem]? { get set } ``` ## Discussion When you get this property’s value, the [`NSURLComponents`](/documentation/Foundation/NSURLComponents) class parses the [`query`](/documentation/Foundation/NSURLComponents/query) string and returns an array of [`NSURLQueryItem`](/documentation/Foundation/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`](/documentation/Foundation/NSURLQueryItem/name) properties of query items are not guaranteed to be unique. If the [`query`](/documentation/Foundation/NSURLComponents/query) property is an empty string, the [`queryItems`](/documentation/Foundation/NSURLComponents/queryItems) property is an empty array. If the [`query`](/documentation/Foundation/NSURLComponents/query) property is `nil`, the [`queryItems`](/documentation/Foundation/NSURLComponents/queryItems) property is also `nil`. When you set this property’s value, the [`NSURLComponents`](/documentation/Foundation/NSURLComponents) class joins each name/value pair with a `=` delimiter and joins the array with a `&` delimiter, then sets the [`query`](/documentation/Foundation/NSURLComponents/query) property to the resulting string. Setting the [`queryItems`](/documentation/Foundation/NSURLComponents/queryItems) property to an empty array sets the [`query`](/documentation/Foundation/NSURLComponents/query) property to an empty string, and setting the [`queryItems`](/documentation/Foundation/NSURLComponents/queryItems) property to `nil` sets the [`query`](/documentation/Foundation/NSURLComponents/query) property to `nil`. > Note: > [RFC 3986](https://www.ietf.org/rfc/rfc3986.txt) 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](https://www.w3.org/Addressing/URL/4_URI_Recommentations.html), 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](https://www.ietf.org/rfc/rfc3339.txt) 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`](/documentation/Foundation/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`](/documentation/Foundation/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`. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)