Use a custom UIView that you designed in IB as a building block in another ViewController

MyView.swift

//This is a valuable method to accomplish the following:
//  You designed your view, MyView, in IB in its own .xib
//  You have a VC, MyViewController, on which you want to lay out 1 or more MyView elements

//Here are the steps to follow after your view + VC have been laid out:
//  In IB on MyViewController, lay out a placeholder View  and set its custom class to MyView
//  In IB on MyView, ensure the file's owner is set to MyView
//    (It then becomes unnecessary to set the custom class on MyView in IB. Let it think it's just a UIView)

import UIKit

class MyView: UIView {
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
		
        let nib = UINib(nibName: "MyView", bundle: Bundle.main)
        let view = nib.instantiate(withOwner: self, options: nil).first as! UIView
        view.frame = bounds
        insertSubview(view, at: 0)
    }
}

MyViewController.swift

//No further code is required in your VC! Just drag your outlet to your MyView(s) and use them as normal

import UIKit

final class MyViewController: UIViewController {
    @IBOutlet weak var view: MyView!
}