MotionRuntime.visualizationElement specification

This is the engineering specification for the MotionRuntime’s visualizationElement API.

Overview

The visualizationElement API is a lazily-created element that’s registered to the MotionRuntime’s container element. This element can be provided to the visualize(in: Element) operator, allowing you to add visualization labels to the visualization element.

MVP

Lazily create the visualization element and store it on the runtime

This element should be added to the runtime’s container element. This element should be stored on the runtime.

class MotionRuntime {
  public var visualizationView: UIView {
    if let visualizationView = _visualizationView {
      return visualizationView
    }

    let view = UIView(frame: .init(x: 0, y: containerView.bounds.maxY, width: containerView.bounds.width, height: 0))
    view.autoresizingMask = [.flexibleWidth, .flexibleTopMargin]
    view.isUserInteractionEnabled = false
    view.backgroundColor = UIColor(white: 0, alpha: 0.1)
    containerView.addSubview(view)
    _visualizationView = view

    return view
  }
  private var _visualizationView: UIView?
}

Remove the visualization element when the runtime terminates

Ensure that you remove the visualization element when the runtime terminates.

class MotionRuntime {
  deinit {
    _visualizationView?.removeFromSuperview()
  }