NibView.swift

//
//  NibView.swift
//  YumaApp
//
//  https://medium.com/theappspace/swift-custom-uiview-with-xib-file-211bb8bbd6eb
//

import UIKit

class NibView: UIView {
	var view: UIView!
	override init(frame: CGRect) {
		super.init(frame: frame)
		
		// Setup view from .xib file
		xibSetup()
	}
	
	required init?(coder aDecoder: NSCoder) {
		super.init(coder: aDecoder)
		
		// Setup view from .xib file
		xibSetup()
	}
}

private extension NibView {
	
	func xibSetup() {
		backgroundColor = UIColor.clear
		view = loadNib()
		// use bounds not frame or it'll be offset
		view.frame = bounds
		// Adding custom subview on top of our view
		addSubview(view)
		
		view.translatesAutoresizingMaskIntoConstraints = false
		addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|[childView]|",
													  options: [],
													  metrics: nil,
													  views: ["childView": view]))
		addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|[childView]|",
													  options: [],
													  metrics: nil,
													  views: ["childView": view]))
	}
}

extension UIView {
	/** Loads instance from nib with the same name. */
	func loadNib() -> UIView {
		let bundle = Bundle(for: type(of: self))
		let nibName = type(of: self).description().components(separatedBy: ".").last!
		let nib = UINib(nibName: nibName, bundle: bundle)
		return nib.instantiate(withOwner: self, options: nil).first as! UIView
	}
}