To load a UITableViewCell or UICollectionViewCell by the class name, avoiding ! operator and using a string literal for the name of the cell identifier Raw

UITableView+Load.swift

//
//  UITableView+Load.swift
//
//  Created by Rigoberto Sáenz Imbacuán (https://www.linkedin.com/in/rsaenzi/)
//  Copyright © 2019. All rights reserved.
//

import UIKit

extension UITableView {

    /**
     Registers a UITableViewCell on this UITableView using the UITableViewCell class name as Reuse Identifier
     Usage: table.registerCell(CellClass.self)
     */
    func registerCell<T: UITableViewCell>(_ cell: T.Type) {
        register(cell, forCellReuseIdentifier: cell.getReuseIdentifier())
    }

    func registerHeader<T: UITableViewHeaderFooterView>(_ cell: T.Type) {
        register(cell, forHeaderFooterViewReuseIdentifier: cell.getReuseIdentifier())
    }
    
    /**
     Dequeues a UITableViewCell from current UITableView only if the UITableViewCell class and the cell Identifier are the same
     Usage: let cell: CellClass = table.dequeue(indexPath)
     */
    func dequeueCell<T: UITableViewCell>(_ indexPath: IndexPath) -> T {

        let identifier = className(some: T.self)
        let rawCell = self.dequeueReusableCell(withIdentifier: identifier, for: indexPath)

        guard let cell = rawCell as? T else {
            fatalError("UITableViewCell with identifier '\(identifier)' was not found")
            //return T(frame: .zero)
        }
        return cell
    }

    func dequeueHeader<T: UITableViewHeaderFooterView>() -> T {

        let identifier = className(some: T.self)
        let rawHeader = self.dequeueReusableHeaderFooterView(withIdentifier: identifier)

        guard let header = rawHeader as? T else {
            fatalError("UITableViewHeaderFooterView with identifier '\(identifier)' was not found")
            //return T(frame: .zero)
        }
        return header
    }
}

extension UICollectionView {

    /**
     Registers a UICollectionViewCell on this UICollectionView using the UICollectionViewCell class name as Reuse Identifier
     */
    func registerCell<T: UICollectionViewCell>(_ cell: T.Type) {
        register(cell, forCellWithReuseIdentifier: T.getReuseIdentifier())
    }
    
    /**
     Dequeues a UICollectionViewCell from current UICollectionView only if the UICollectionViewCell class and the cell Identifier are the same
     */
    func dequeueCell<T: UICollectionViewCell>(_ indexPath: IndexPath) -> T {
        
        let identifier = className(some: T.self)
        let rawCell = self.dequeueReusableCell(withReuseIdentifier: identifier, for: indexPath)
        
        guard let cell = rawCell as? T else {
            fatalError("UICollectionViewCell with identifier '\(identifier)' was not found")
            //return T(frame: .zero)
        }
        return cell
    }
}

extension UITableViewCell {
    
    fileprivate static func getReuseIdentifier() -> String {
        return className(some: self)
    }
}

extension UITableViewHeaderFooterView {
    
    fileprivate static func getReuseIdentifier() -> String {
        return className(some: self)
    }
}

extension UICollectionViewCell {
    
    fileprivate static func getReuseIdentifier() -> String {
        return className(some: self)
    }
}

private func className(some: Any) -> String {
    return (some is Any.Type) ? "\(some)" : "\(type(of: some))"
}

UIView+Load.swift
https://gist.github.com/rsaenzi/0c3da9a1f5084c6ac73cee0b501daf33

CustomCell.swift
https://gist.github.com/rsaenzi/e2ab2c4e78ee7ba12c9b534ec4982530