Type-safe-tableView.swift

// ### Con's of the UITableView's `register` and `dequeue` methods
// - You have to use String for `reusableIdentifier`.
// - The interfaces for nib and class are different.
// - When you dequeue cells, you have to cast them as custom classes.

protocol Reusable: class {
    static var reusableIdentifier: String { get }
}

extension Reusable {
    static var reusableIdentifier: String {
        return String(describing: self)
    }
}

protocol NibReusable: Reusable {
    static var nib: UINib { get }
}

extension NibReusable {
    static var nib: UINib {
        let nibName = String(describing: self)
        return UINib(nibName: nibName, bundle: Bundle(for: self))
    }
}

extension UITableView {
    func register<T: Reusable>(_ reusableClass: T.Type) where T: UITableViewCell {
        register(reusableClass, forCellReuseIdentifier: reusableClass.reusableIdentifier)
    }
    
    func register<T: NibReusable>(_ nibReusableClass: T.Type) where T: UITableViewCell {
        register(nibReusableClass.nib, forCellReuseIdentifier: nibReusableClass.reusableIdentifier)
    }
    
    func register<T: Reusable>(_ reusableClass: T.Type) where T: UITableViewHeaderFooterView {
        register(reusableClass, forHeaderFooterViewReuseIdentifier: reusableClass.reusableIdentifier)
    }
    
    func register<T: NibReusable>(_ nibReusableClass: T.Type) where T: UITableViewHeaderFooterView {
        register(nibReusableClass.nib, forHeaderFooterViewReuseIdentifier: nibReusableClass.reusableIdentifier)
    }
    
    func dequeueReusableCell<T: Reusable>(_ reusableClass: T.Type) -> T where T: UITableViewCell {
        guard let cell = dequeueReusableCell(withIdentifier: reusableClass.reusableIdentifier) as? T else {
            fatalError("Unknown class type for cell, \(reusableClass)")
        }
        return cell
    }
    
    func dequeueReusableCell<T: Reusable>(_ reusableClass: T.Type, for indexPath: IndexPath) -> T where T: UITableViewCell {
        guard let cell = dequeueReusableCell(withIdentifier: reusableClass.reusableIdentifier, for: indexPath) as? T else {
            fatalError("Unknown class type for cell, \(reusableClass)")
        }
        return cell
    }
    
    func dequeueReusableHeaderFooterView<T: Reusable>(_ reusableClass: T.Type) -> T where T: UITableViewHeaderFooterView {
        guard let headerFooterView = dequeueReusableHeaderFooterView(withIdentifier: reusableClass.reusableIdentifier) as? T else {
            fatalError("Unknown class type for cell, \(reusableClass)")
        }
        return headerFooterView
    }
}