UITableView+IdentifierDequeueableCell.swift

import UIKit

protocol IdentifierDequeueableCell where Self: UITableViewCell {
    static var dequeueIdentifier: String { get }
}

extension IdentifierDequeueableCell {
    static var dequeueIdentifier: String {
        return String(describing: self)
    }
}

extension UITableView {

    func dequeueReusableCell<T: IdentifierDequeueableCell>(withType: T.Type, for indexPath: IndexPath) -> T {
        let cell = dequeueReusableCell(withIdentifier: T.dequeueIdentifier, for: indexPath)
        guard let typedCell = cell as? T else {
            preconditionFailure("Cell is not correct type")
        }
        return typedCell
    }

}

Usage.swift

// Normally

guard let cell = tableView.dequeueReusableCell(withIdentifier: "MyCellSubclass", for: indexPath) as? MyCellSubclass else {
    preconditionFailure("dequeue gave back nil or wrong cell type!")
}
return cell

// With extension

return tableView.dequeueReusableCell(withType: MyCellSubclass.type, for: indexPath)