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Property · Interaction Tap
Status Library
Draft as of December 20, 2016 interactions

Tap specification

This is the engineering specification for the Tap interaction.


The tap interaction writes to a position property when a tap gesture is recognized.

Example use:

let tap = Tap(sets: tossable.destination, containerView: view)


Expose a Tap type

public class Tap: Interaction

Expose configurable values

All property values should be readonly, all stream values should be settable.

class Tap {

  /** The position to which the position stream is expected to write. */
  public let position: ReactiveProperty<CGPoint>

  /** A stream that emits positional values to be written to the view. */
  public var positionStream: MotionObservable<CGPoint>

Expose an initializer

class Tap {
  public init(sets position: ReactiveProperty<CGPoint>,
                containerView: UIView,
                tapGestureRecognizer: UITapGestureRecognizer? = nil)

Store the position

class Tap {
  init(...) {
    self.position = position


Create a tap gesture recognizer if one was not provided

class Tap {
  init(...) {

    let tapGestureRecognizer = tapGestureRecognizer ?? UITapGestureRecognizer()
    if tapGestureRecognizer.view == nil {


Create the position stream

class Tap {
  init(...) {

    self.positionStream = gestureSource(tapGestureRecognizer)
      .centroid(in: containerView)