ARView+SelfSceneRecordable.swift

//
//  ARView.swift
//  SCNRecorder
//
//  Created by Vladislav Grigoryev on 17.08.2020.
//  Copyright © 2020 GORA Studio. All rights reserved.
//
//  Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the "Software"), to deal
//  in the Software without restriction, including without limitation the rights
//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
//  copies of the Software, and to permit persons to whom the Software is
//  furnished to do so, subject to the following conditions:
//
//  The above copyright notice and this permission notice shall be included in
//  all copies or substantial portions of the Software.
//
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
//  THE SOFTWARE.

import Foundation
import RealityKit
import SCNRecorder
import Combine

private var cancellableKey: UInt8 = 0

@available(iOS 13.0, *)
extension ARView: SelfSceneRecordable {

  var _cancelable: Cancellable? {
    get {
      objc_getAssociatedObject(
        self,
        &cancellableKey
      ) as? Cancellable
    }
    set {
      objc_setAssociatedObject(
        self,
        &cancellableKey,
        newValue,
        .OBJC_ASSOCIATION_RETAIN
      )
    }
  }

  public func injectRecorder() {
    do {
      sceneRecorder = try SceneRecorder(self)

      #if !targetEnvironment(simulator)
      session.delegate = sceneRecorder
      #endif

      _cancelable?.cancel()
      _cancelable = scene.subscribe(
        to: SceneEvents.Update.self
      ) { [weak sceneRecorder] (_) in
        sceneRecorder?.render()
      }
    }
    catch { assertionFailure("\(error)") }
  }
}