> ## Documentation Index
> Fetch the complete documentation index at: https://algolia.com/llms.txt
> Use this file to discover all available pages before exploring further.

# RelevantSort

> Lets users switch between search modes, exhaustive or relevant sorting.

export const Facet = () => <Tooltip tip="An attribute in your records that lets users filter or group results (for example, by color, brand, or price)." cta="Faceting" href="/doc/guides/managing-results/refine-results/faceting">
    facet
  </Tooltip>;

```swift Signature theme={"system"}
RelevantSortConnector<Controller: RelevantSortController, Output>(
  searcher: SingleIndexSearcher,
  interactor: RelevantSortInteractor,
  controller: Controller,
  presenter: RelevantSortPresenter<Output>
)

RelevantSortConnector<Controller: RelevantSortController, Output>(
  searcher: SingleIndexSearcher,
  interactor: RelevantSortInteractor,
  controller: Controller,
  presenter: RelevantSortTextualPresenter
)
```

<Card title="Explore example code" icon="github" href="https://github.com/algolia/instantsearch-ios/tree/master/Examples/Showcase">
  Browse the RelevantSort example code on GitHub.
</Card>

## About this widget

Virtual indices let you use [relevant sort](/doc/guides/managing-results/refine-results/sorting/in-depth/relevant-sort),
a sorting mechanism that favors relevancy over the attribute you're sorting on.
The `relevantSort` widget displays the current search mode when searching in a virtual replica index,
and allows users to switch between relevant and regular sorting,
which is more exhaustive but can return less relevant results.

## Examples

Instantiate a `RelevantSortConnector`.

```swift Swift icon=code theme={"system"}
let searcher = HitsSearcher(appID: "YourApplicationID",
                            apiKey: "YourSearchOnlyAPIKey",
                            indexName: "virtual_replica_index")
let relevantSortController: ButtonRelevantSortController = .init()
let relevantSortConnector: RelevantSortConnector = .init(searcher: searcher, controller: relevantSortController)
```

## Parameters

<ResponseField name="searcher" type="HitsSearcher" required>
  The [`Searcher`](/doc/api-reference/widgets/instantsearch/ios) that handles your searches.
</ResponseField>

<ResponseField name="interactor" type="RelevantSortInteractor" post={["default: .init()"]} required>
  The logic to toggle relevant Sort.
</ResponseField>

<ResponseField name="controller" type="RelevantSortController" post={["default: nil"]}>
  Controller that presents and can toggle the Relevant Sort priority state.
</ResponseField>

<ResponseField name="presenter" type="RelevantSortPresenter<Output> | RelevantSortTextualPresenter" post={["default: DefaultPresenter.RelevantSort.present"]} required>
  Presenter transforming the Relevant sort priority state to its representation for a controller.
</ResponseField>

## Presenter

<ParamField body="RelevantSort Presenter" type="RelevantSortPresenter<Output> | RelevantSortTextualPresenter" default="DefaultPresenter.RelevantSort.present" required>
  Presenter transforming the relevant sort priority state to its representation for a controller.
  Default presenter transforms relevant sort priority to `RelevantSortTextualRepresentation?`
  providing a tuple of string constants in English.

  ```swift Swift icon=code theme={"system"}
  public static func present(_ priority: RelevantSortPriority?) -> RelevantSortTextualRepresentation? {
      switch priority {
      case .some(.hitsCount):
        return ("Currently showing all results.", "Show more relevant results")
      case .some(.relevancy):
        return ("We removed some search results to show you the most relevants ones.", "Show all results")
      default:
        return nil
      }
    }
  ```
</ParamField>

## Low-level API

If you want to fully control the `RelevantSort` components and connect them manually,
you can use the following components:

* `Searcher`. The [`Searcher`](/doc/api-reference/widgets/instantsearch/ios) that handles your searches.
* `RelevantSortInteractor`. Relevant sort priority toggling logic.
* `RelevantSortController`. The controller that presents and toggles the Relevant sort priority state.
* `RelevantSortPresenter<Output>`. Optional. Generic presenter transforming the Relevant Sort priority state to its representation for a controller.

```swift Swift icon=code theme={"system"}
let searcher = HitsSearcher(appID: "YourApplicationID",
                            apiKey: "YourSearchOnlyAPIKey",
                            indexName: "virtual_replica_index")

let relevantSortInteractor = RelevantSortInteractor()
let relevantSortController: ButtonRelevantSortController = .init()

relevantSortInteractor.connectSearcher(searcher)

let relevantSortpresenter: RelevantSortTextualPresenter = { priority in
  switch priority {
  case .some(.hitsCount):
    return ("Currently showing all results.", "Show more relevant results")
  case .some(.relevancy):
    return ("We removed some search results to show you the most relevants ones.", "Show all results")
  default:
    return nil
  }
}

relevantSortInteractor.connectController(relevantSortController, presenter: relevantSortpresenter)
```

## Customizing your view

The controllers provided by default,
like the `ButtonRelevantSortController` work well when you want to use native UIKit with their default behavior like a `UIButton`.

If you want to use another component,
a third-party input view,
or you want to introduce some custom behavior to the already provided UIKit component,
you can create your own controller conforming to the `RelevantSortController` protocol.

### Protocol

`func setItem(_ item: RelevantSortTextualRepresentation?)`

Function called when a new array of indices is defined.

`var didToggle: (() -> Void)? { get set }`

Closure triggered by the controller when the toggle happens (for example, toggle button clicked or switch control state changed)

### Example

```swift Swift icon=code theme={"system"}
public class RelevantSortControl: NSObject, RelevantSortController {

  public let hintLabel: UILabel
  public let toggleButton: UIButton

  public var didToggle: (() -> Void)?

  public init() {
    hintLabel = .init()
    toggleButton = .init()
    super.init()
    toggleButton.addTarget(self, action: #selector(didTapToggleButton), for: .touchUpInside)
  }

  public func setItem(_ item: RelevantSortTextualRepresentation?) {
    hintLabel.isHidden = item == nil
    toggleButton.isHidden = item == nil
    hintLabel.text = item?.hintText
    toggleButton.setTitle(item?.toggleTitle, for: .normal)
  }

  @objc func didTapToggleButton() {
    didToggle?()
  }

}
```

### SwiftUI

InstantSearch provides the `RelevantSortObservableController` data model,
which is an implementation of the `RelevantSortController` protocol adapted for usage with SwiftUI.
`RelevantSortObservableController` must be connected to the `RelevantSortConnector` or `RelevantSortInteractor` like any other `RelevantSortController` implementation.

The example of the SwiftUI view presenting the relevant sort state.

```swift Swift icon=code theme={"system"}
  struct ContentView: View {

  @ObservedObject var relevantSortController: RelevantSortObservableController

  var body: some View {
    VStack {
      if let state = relevantSortController.state {
        HStack {
          Text(state.hintText)
          Spacer()
          Button(state.toggleTitle,
                 action: relevantSortController.toggle)
        }
      }
    }
  }

}
```

If you prefer to create a custom SwiftUI view that presents each <Facet />,
use the `RelevantSortObservableController` as a data model.
It provides the `state` property along with the `toggle` function to streamline the design process of your custom SwiftUI view.