Cells reusableIdentifier and nib utility extension

CellUtilities-Swift2.2.swift

import Foundation
import UIKit

public protocol Reusable: class, NSObjectProtocol {
    static var reusableIdentifier: String { get }
}
public extension Reusable {
    public static var reusableIdentifier: String { return String(Self) }
}

public protocol Nibable: class, NSObjectProtocol {
    static var nib: UINib { get }
    static var nibName: String { get }
}
public extension Nibable {
    public static var nib: UINib { return UINib(nibName: String(Self), bundle: NSBundle(forClass: self)) }
    public static var nibName: String { return String(Self) }
    public static func fromNib<T : UIView>() -> T? { return UINib(nibName: String(Self), bundle: NSBundle(forClass: self)).instantiateWithOwner(nil, options: nil).flatMap { $0 as? T }.first }
}

extension UIView: Nibable { }
extension UIViewController: Nibable { }

extension UITableViewCell: Reusable { }
extension UITableViewHeaderFooterView : Reusable { }
extension UICollectionReusableView: Reusable { }

CellUtilities-Swift3.0.swift

import Foundation
import UIKit

public protocol Reusable: class, NSObjectProtocol {
    static var reusableIdentifier: String { get }
}
public extension Reusable {
    public static var reusableIdentifier: String {
        return String(describing: Self.self)
    }
}

public protocol Nibable: class, NSObjectProtocol {
    static var nib: UINib { get }
    static var nibName: String { get }
}
public extension Nibable {
    public static var nib: UINib { return UINib(nibName: String(describing: Self.self), bundle: Bundle(for: self)) }
    public static var nibName: String { return String(describing: Self.self) }
}

extension UITableViewCell: Reusable, Nibable { }
extension UICollectionReusableView: Reusable, Nibable { }