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Signature
TagFilterListConnector(
  tagFilters: [TagFilter],
  selectionMode: SelectionMode,
  filterState: FilterState,
  operator: RefinementOperator,
  groupName: String,
  controller: FilterListTableController<Filter.Tag>
)
Explore example code

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About this widget

TagFilterList is a filtering component that displays tag filters and lets users refine the search results by selecting them. Compared to the RefinementList, which takes its values from the search response , this widget displays tag filters that you add yourself.

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Examples

Instantiate a TagFilterListConnector and launch an initial search on its Searcher.
Swift
let searcher = HitsSearcher(appID: "YourApplicationID",
                            apiKey: "YourSearchOnlyAPIKey",
                            indexName: "YourIndexName")

let filterState = FilterState()

let filters: [Filter.Tag] = [
  "coupon",
  "free shipping",
  "free return",
  "on sale",
  "no exchange"
]
let filterListTableView: UITableView = .init()
let filterListController: FilterListTableController<Filter.Tag> = .init(tableView: filterListTableView)

let filterListConnector = TagFilterListConnector(tagFilters: filters,
                                                 selectionMode: .multiple,
                                                 filterState: filterState,
                                                 operator: .and,
                                                 groupName: "Tag Filters",
                                                 controller: filterListController)

searcher.connectFilterState(filterState)
searcher.search()

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Parameters

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tagFilters
[TagFilter]
required
The tag filters to display.
​
selectionMode
SelectionMode
Whether a user can select .single or .multiple values.
​
filterState
FilterState
required
The FilterState that holds your filters.
​
operator
RefinementOperator
required
Whether to apply an and or or behavior to the filters in the filter state.For example with or, the filter sent to Algolia is _tags:promo OR color:green.
​
groupName
String
required
Filter group name.
​
controller
FilterListTableController<Filter.Tag>
Controller interfacing with a concrete filter list view.

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Low-level API

If you want to fully control the TagFilterList components and connect them manually, you can use the following components:
  • Searcher. The Searcher that handles your searches.
  • FilterState. The current state of the filters.
  • TagFilterListInteractor. The logic applied to the tag filters.
  • FilterListController. The view that will render the tag filters.
Swift
let searcher = HitsSearcher(appID: "YourApplicationID",
                            apiKey: "YourSearchOnlyAPIKey",
                            indexName: "YourIndexName")

let filterState = FilterState()

let filters: [Filter.Tag] = [
  "coupon",
  "free shipping",
  "free return",
  "on sale",
  "no exchange"
]
let filterListTableView: UITableView = .init()
let filterListController: FilterListTableController<Filter.Tag> = .init(tableView: filterListTableView)

let filterListInteractor = TagFilterListInteractor(items: filters,
                                                  selectionMode: .multiple)

filterListInteractor.connectFilterState(filterState, operator: .and, groupName: "Tag Filters")
filterListInteractor.connectController(filterListController)

searcher.connectFilterState(filterState)
searcher.search()

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Customizing your view

The default controllers, such as the FilterListTableController, work well when you want to use native UIKit with their default behavior. If you want to use another component such as a UICollectionView, 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 TagFilterListController protocol.

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Protocol

var onClick: ((Filter.Tag) -> Void)?: Closure to call when a filter is clicked. func setSelectableItems(selectableItems: [SelectableItem<Filter.Tag>]) Function called when a new array of selectable facets is updated. This is the UI State of the refinement list. func reload() Function called when we require a reload of the list view.

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Implementation example

Swift
class TagFilterListTableController: NSObject, TagFilterListController, UITableViewDataSource, UITableViewDelegate {

  public var onClick: ((Filter.Tag) -> Void)?

  public let tableView: UITableView

  public var selectableItems: [SelectableItem<Filter.Tag>] = []
  public var filterPresenter: FilterPresenter?

  let cellID: String

  public init(tableView: UITableView, cellID: String = "cellID") {
    self.tableView = tableView
    self.cellID = cellID
    super.init()
    tableView.dataSource = self
    tableView.delegate = self
    tableView.register(UITableViewCell.self, forCellReuseIdentifier: cellID)
  }

  // MARK: - FilterListController

  public func setSelectableItems(selectableItems: [SelectableItem<Filter.Tag>]) {
    self.selectableItems = selectableItems
  }

  public func reload() {
    tableView.reloadData()
  }

  // MARK: - UITableViewDataSource

  func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return selectableItems.count
  }

  func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: cellID, for: indexPath)
    let filter = selectableItems[indexPath.row]
    let filterPresenter = self.filterPresenter ?? DefaultPresenter.Filter.present
    cell.textLabel?.text = filterPresenter(Filter(filter.item))
    cell.accessoryType = filter.isSelected ? .checkmark : .none

    return cell
  }

  // MARK: - UITableViewDelegate

  func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    let selectableItem = selectableItems[indexPath.row]
    onClick?(selectableItem.item)
  }

}

​
SwiftUI

InstantSearch provides the FilterList SwiftUI view which you can embed in your views. It uses FilterListObservableController as a data model, which is an implementation of the SelectableListController protocol adapted for usage with SwiftUI. FilterListObservableController must be connected to the TagFilterListConnector or TagFilterListInteractor like any other SelectableListController implementation. You have to define the appearance of the view representing a single tag filter and its selection state.
Swift
struct ContentView: View {

  @ObservedObject var filterListController: FilterListObservableController<Filter.Tag>

  var body: some View {
    FilterList(filterListController) { filter, isSelected in
      // declare the view presenting a single tag filter and its selection state
      HStack {
        Text(filter.value.description)
        Spacer()
        if isSelected {
          Image(systemName: "checkmark")
            .foregroundColor(.accentColor)
        }
      }
      .contentShape(Rectangle())
      .frame(idealHeight: 44)
      .padding(.horizontal, 5)
    }
  }
}
If you prefer to create a custom SwiftUI view that presents the list of tag filters, you can directly use the FilterListObservableController<Filter.Tag> as a data model. It provides filters and selections properties along with toggle and isSelected functions to streamline the design process of your custom SwiftUI view.