Workaround for UICollectionViewCell+RCTRootView

UICollectionViewCell+RCTRootViewDemo.swift

import Dispatch
import Foundation
import UIKit

extension DispatchQueue {
    /// Run the action immediately if it's on the main thread, otherwise dispatch it to the main thread asynchronously.
    public static func onMainThread(_ action: @escaping () -> Void) {
        if Thread.isMainThread {
            action()
        } else {
            DispatchQueue.main.async {
                action()
            }
        }
    }
    
    /// Run the action immediately if it's on the main queue, otherwise dispatch it to the main queue asynchronously.
    public static func onMainQueue(_ action: @escaping () -> Void) {
        if Thread.isMainThread && DispatchQueue.currentQueueLabel == DispatchQueue.main.label {
            action()
        } else {
            DispatchQueue.main.async {
                action()
            }
        }
    }
    
    private static var currentQueueLabel: String {
        let label = __dispatch_queue_get_label(nil)
        return String(cString: label)
    }
}

class DemoCell: UICollectionViewCell {
    override init(frame: CGRect) {
        super.init(frame: frame)
        setupView()
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    private var rnView: UIView!
    
    private func setupView() {
        // RCTRootView expectes to be run on the main queue
        DispatchQueue.onMainQueue { [self] in
            rnView = RCTRootView(...)
            contentView.addSubview(rnView)
        }
    }
}