Instantiate and use in code a custom UIView subclass that you designed in IB

MyView.swift

//MyView was designed in IB (xib not included in this gist)
//  In IB, you need not set the file's owner, as Bundle.main.loadNibNamed() sets that for you.
//  You should, however, still set its custom class on the View

import UIKit

class MyView: UIView {
	class func createFromNib() -> MyView {
		//loadNibNamed returns all of the top-level objects in that nib, but .first is always your UIView object
		return Bundle.main.loadNibNamed("MyView", owner: self, options: nil)?.first as! MyView
	}
}

MyViewController.swift

//For example, if your VC contains a stack view, you may want to programmatically add to it a subview that you designed in IB

import UIKit

final class MyViewController: UIViewController {
	@IBOutlet weak var stackView: UIStackView!	
	
	override func viewDidLoad() {
		stackView.addArrangedSubview(MyView.createFromNib())
    }
}