Protocol used by a UIView subclass for xibs

NibViewType.swift

import UIKit

/**
 The adopting UIView is the File Ower of a nib by the same name. All IBOutlets are wired through the File Owner (not the content view itself) and the content view is also wired to the IBOutlet `view`.

 NOTE - `loadFromNib:` must be called within a convenience initializer.

 Keep in mind that any UIView instance method that you would normally use `self` should be called `view` instead.
 */
protocol NibViewType: UIAppearance {
    var view: UIView! { get set }
    func loadFromNib()
}

extension NibViewType where Self: UIView {

    func loadFromNib() {
        if let identifier = NSStringFromClass(self.classForCoder).components(separatedBy: ".").last {

            Bundle.main.loadNibNamed(identifier, owner: self, options: nil)
            view.frame = self.frame
            addSubview(view)
        } else {
            assertionFailure("View could not be loaded from a nib. Make sure that the nib file shares the same name as the view class that is the file's owner and that the content view is mapped to owner's view IBOutlet.")
        }
    }
}