An async version of RealityKit's Entity/move that returns when the animation completes

Entity+MoveAsync.swift

//
//  Entity+MoveAsync.swift
//
//  Created by Drew Olbrich on 1/15/24.
//  Copyright © 2024 Lunar Skydiving LLC. All rights reserved.
//
//  MIT License
//  
//  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 Combine

extension Entity {
    
    /// Asynchronously moves an entity over a period of time to a new location given by
    /// a transform.
    ///
    /// - Parameters:
    ///   - target: A `Transform` instance that indicates the new location.
    ///   - referenceEntity: The entity that defines a frame of reference. Set
    /// this to `nil` to indicate world space.
    ///   - duration: The time in seconds over which the move should occur.
    ///   - timingFunction: A timing function that controls the progress of the
    /// animation.
    @MainActor func moveAsync(to target: Transform, relativeTo referenceEntity: Entity?, duration: TimeInterval, timingFunction: AnimationTimingFunction = .default) async {
        guard let scene else {
            return
        }
        let animationPlaybackController = move(to: target, relativeTo: referenceEntity, duration: duration, timingFunction: timingFunction)
        
        // Updates for Swift 6 below by Luca Ban (@mesqueeb).
        let publisher = scene.publisher(for: AnimationEvents.PlaybackCompleted.self, on: self)
        await withCheckedContinuation { continuation in
            Task {
                for await event in publisher.values {
                    if event.playbackController == animationPlaybackController { continuation.resume() }
                }
            }
        }
    }
    
}