Filter Numeric Range

Lets users refine results between two numeric values using a slider.

Signature

NumberRangeConnector<Number>(
  filterState: FilterState,
  attribute: Attribute,
  bounds: ClosedRange<Number>?,
  range: ClosedRange<Number>,
  operator: RefinementOperator,
  groupName: String?,
  controller: NumberRangeController
)

Explore example code

Browse the Filter Numeric Range example code on GitHub.

About this widget

Filter Numeric Range is a filtering component made to filter between two numeric values. The most common interface for this is a slider.

Examples

Instantiate a NumberRangeConnector and launch an initial search on its searcher.

Swift

let searcher = HitsSearcher(appID: "YourApplicationID",
                            apiKey: "YourApiKey",
                            indexName: "YourIndexName")
let filterState: FilterState = .init()

let numberRangeController: RangeSliderController = .init(rangeSlider: .init())

let numericRangeConnector: NumberRangeConnector<Double> = .init(searcher: searcher,
                                                                filterState: filterState,
                                                                attribute: "price",
                                                                controller: numberRangeController)

searcher.search()

Parameters

searcher · HitsSearcher · required

The Searcher that handles your searches.

filterState · FilterState · required

The FilterState that holds your filters.

attribute · Attribute · required

The attribute to filter.

interactor · NumberRangeInteractor<Number> · required · default: .init()

The logic applied to the numeric range.

bounds · ClosedRange<Number>? · default: nil

The nounds limiting the max and the min value of the range.

range · ClosedRange<Number> · default: nil

The initial range value.

operator · RefinementOperator · default: .and

Whether the filter is added to a conjuncitve(and) or a disjuncitve (or) group in the filter state.

groupName · String · default: The value of the `attribute` parameter

Filter group name in the FilterState

controller · NumberRangeController · default: nil

The Controller interfacing with a concrete number range view.

Low-level API

If you want to fully control the Filter Numeric Range 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.
• NumberRangeInteractor. The logic applied to the numeric ranges.
• NumberRangeController. The controller that interfaces with a concrete numeric range view.

Swift

let searcher = HitsSearcher(appID: "YourApplicationID",
                            apiKey: "YourApiKey",
                            indexName: "YourIndexName")
let filterState: FilterState = .init()

let numericRangeInteractor: NumberRangeInteractor<Double> = .init()
let numberRangeController: RangeSliderController = .init(rangeSlider: .init())

let priceAttribute: Attribute = "price"

searcher.connectFilterState(filterState)

numericRangeInteractor.connectFilterState(filterState, attribute: priceAttribute)
numericRangeInteractor.connectSearcher(searcher, attribute: priceAttribute)
numericRangeInteractor.connectController(numberRangeController)

searcher.search()

Customizing your view

If you want to use 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 NumberRangeController protocol.

Protocol

func setBounds(_ bounds: ClosedRange<Double>):

Function called when the minimum and maximum of numeric filter view have been defined.

var onRangeChanged: ((ClosedRange<Double>) -> Void)?

Closure to call when new bounds is set for the numeric range filter.

Example

Suppose you have a range slider control providing the following API:

Swift

class RangeSlider: UIControl {
  var lowerValue: Double
  var upperValue: Double
  var minimumValue: Double
  var maximumValue: Double
}

Then, you could implement the NumberRangeController including this control as follows:

Swift

class RangeSliderController: NumberRangeController {

  let rangeSlider: RangeSlider

  var onRangeChanged: ((ClosedRange<Double>) -> Void)?

  func setBounds(_ bounds: ClosedRange<Double>) {
    rangeSlider.minimumValue = bounds.lowerBound
    rangeSlider.maximumValue = bounds.upperBound
    setItem(bounds)
  }

  func setItem(_ item: ClosedRange<Double>) {
    rangeSlider.lowerValue = item.lowerBound
    rangeSlider.upperValue = item.upperBound
  }

  init(rangeSlider: RangeSlider) {
    self.rangeSlider = rangeSlider
    rangeSlider.addTarget(self, action: #selector(onValueChanged(sender:)), for: [.touchUpInside, .touchUpOutside])
  }

  @objc func onValueChanged(sender: RangeSlider) {
    onRangeChanged?(sender.lowerValue...sender.upperValue)
  }

}

SwiftUI

InstantSearch provides the NumberRangeObservableController data model, which is an implementation of the NumberRangeController protocol adapted for usage with SwiftUI. NumberRangeObservableController must be connected to the NumberRangeConnector or NumberRangeConnector like any other NumberRangeController implementation.

The example of the number range view using two Stepper components provided by SwiftUI.

Swift

struct ContentView: View {

  @ObservedObject var numberRangeController: NumberRangeObservableController<Int>

  var body: some View {
    let range = numberRangeController.range
    VStack{
      Stepper(onIncrement: {
        if let range = makeRange(range.lowerBound+1, range.upperBound) {
          numberRangeController.range = range
        }
      },
      onDecrement: {
        if let range = makeRange(range.lowerBound-1, range.upperBound) {
          numberRangeController.range = range
        }
      },
      label: {
        Text("Lower bound: \(range.lowerBound)")
      })
      Stepper(onIncrement: {
        if let range = makeRange(range.lowerBound, range.upperBound+1) {
          numberRangeController.range = range
        }
      },
      onDecrement: {
        if let range = makeRange(range.lowerBound, range.upperBound-1) {
          numberRangeController.range = range
        }
      },
      label: {
        Text("Upper bound: \(numberRangeController.range.upperBound)")
      })
    }
  }

  func makeRange(_ lowerBound: Int, _ upperBound: Int) -> ClosedRange<Int>? {
    if lowerBound < upperBound &&
       numberRangeController.bounds.contains(lowerBound) &&
       numberRangeController.bounds.contains(upperBound) {
      return lowerBound...upperBound
    } else {
      return nil
    }
  }

}

If you prefer to create a custom SwiftUI view that presents the numeric range, you can directly use the NumberRangeObservableController as a data model. It provides range and bounds properties to streamline the design process of your custom SwiftUI view.