API Reference / InstantSearch iOS Widgets / Sort By
Aug. 23, 2019

About this widget

SortBy displays a list of indices, allowing a user to change the way hits are sorted (using replica indices). Another common use case is to let the user switch between different indices to show different results.

For this to work, you must define all indices that you pass to SortBy as replicas of the main index.

To add SortBy to your search experience, use these components:

  • Searcher: The Searcher that handles your searches.
  • IndexSegmentInteractor: The logic applied to the index sorting/switching.
  • SelectableSegmentController: The controller that interfaces with a concrete index list.
  • IndexPresenter: Optional. The presenter that converts an Index to a String output.

Examples

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
let alert = UIAlertController(title: "Change Index", message: "Please select a new index", preferredStyle: .actionSheet)

let searcher: SingleIndexSearcher = .init(appID: "YourApplicationID",
                                          apiKey: "YourSearchOnlyAPIKey",
                                          indexName: "indexDefault")

let indexSegmentInteractor: IndexSegmentInteractor = {
  let indices [
    0 : indexDefault,
    1 : indexAscendingOrder,
    2 : indexDescendingOrder
  ]
  return .init(items: indices)
}()

lazy var selectIndexController: SelectIndexController = { return .init(alertController: alert) }()

let client: Client = .init(appID: "YourApplicationID", apiKey: "YourSearchOnlyAPIKey")

lazy var indexDefault: Index = { return client.index(withName: "indexDefault") }()
lazy var indexAscendingOrder: Index = { return client.index(withName: "indexAscendingOrder") }()
lazy var indexDescendingOrder: Index =  { return client.index(withName: "indexDescendingOrder") }()

override func viewDidLoad() {
  super.viewDidLoad()
  
  indexSegmentInteractor.connectSearcher(searcher: searcher)
  indexSegmentInteractor.connectController(SelectIndexController(alertController: alert)) { (index) -> String in
    switch index {
    case self.indexDefault: return "Default"
    case self.indexAscendingOrder: return "Year Asc"
    case self.indexDescendingOrder: return "Year Desc"
    default: return index.name
    }
  }
}

Parameters

items
type: [Int: Index]
Required

The list of indices to search in.

1
2
3
4
5
6
7
    let indices [
      0 : indexDefault,
      1 : indexAscendingOrder,
      2 : indexDescendingOrder
    ]
    
    let indexSegmentInteractor: IndexSegmentInteractor = .init(items: indices)

Presenter

Index Presenter
type: IndexPresenter
Optional

The presenter that defines the way we want to display an index, taking as input an Index and returning a String.

1
2
3
public static let present: IndexPresenter = { index in
  return index.name
}

Customize your view

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

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 SelectableSegmentController protocol.

Protocol

func setSelected(_ selected: Int?):

Function called when an index is selected, with the position that is selected.

func setItems(items: [Int: String])

Function called when a new array of indices is defined.

func reload()

Function called when we require a reload of the list view.

var onClick: ((Int) -> Void)?:

Closure to call when a new index is clicked.

Example

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
public class SelectIndexController: NSObject, SelectableSegmentController {

  let alertController: UIAlertController

  public var onClick: ((Int) -> Void)?

  public init(alertController: UIAlertController) {
    self.alertController = alertController
    super.init()
  }

  public func setSelected(_ selected: Int?) {
    // Show a check mark next to the item selected here
  }

  public func setItems(items: [Int: String]) {
    guard alertController.actions.isEmpty else { return }
    for item in items {
      alertController.addAction(UIAlertAction(title: item.value, style: .default, handler: { [weak self] _ in
        self?.onClick?(item.key)
      }))
    }
    alertController.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: .none))
  }

}

Did you find this page helpful?