A RealityKit SceneUpdateContext extension that wraps entities(matching:updateSystemWhen:) but works on both visionOS and iOS

SceneUpdateContext+EntitiesWhenRendering.swift

//
//  SceneUpdateContext+EntitiesWhenRendering.swift
//
//  Created by Drew Olbrich on 7/27/23.
//  Copyright © 2023 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 RealityKit

extension SceneUpdateContext {
    
    /// Returns all entities which pass the `QueryPredicate` of the query for rendering
    /// updates.
    ///
    /// On `visionOS`, this method calls `SceneUpdateContext/entities(matching:when:)`
    /// with `.rendering` for the `condition` parameter.
    ///
    /// On `iOS`, this method calls `SceneUpdateContext/Scene/performQuery(_)`.
    func entitiesWhenRendering(matching query: EntityQuery) -> QueryResult<Entity> {
#if os(visionOS)
        // On visionOS only, this form is recommended.
        // See https://developer.apple.com/wwdc23/10080 at 25:35.
        // "The rendering condition means that this system will update at an appropriate
        // rate for smooth animations".
        return entities(matching: query, updatingSystemWhen: .rendering)
#else // !os(visionOS)
        return scene.performQuery(query)
#endif // !os(visionOS)
    }
    
}