title: MKMapview inside collection view cell not visible
body: <p>I have created a collection view containing 4 cells. In one of them I would like to display a MapView. This is my collection view cell code:</p>
  
  <pre><code>import Foundation
  import UIKit
  import MapKit
  import CoreLocation
  
  class PestañaUno: UICollectionViewCell, CLLocationManagerDelegate, MKMapViewDelegate
  {
      let manager = CLLocationManager()
  
      override init(frame: CGRect)
      {
          super.init(frame: frame)
          Setup()
      }
  
      required init?(coder aDecoder: NSCoder)
      {
          fatalError("init(coder:) has not been implemented")
      }
  
      var Mapa: MKMapView =
      {
          var map = MKMapView()
          map.frame = CGRect(x: 0, y: 0, width: 300, height: 400)
          map.mapType = MKMapType.standard
          return map
      }()
  
      func Setup()
      {
          addSubview(Mapa)
      }
  </code></pre>
  
  <p>And here is when I try to call that collectionviewcell code. </p>
  
  <pre><code>func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -&gt; UICollectionViewCell
  {
      if indexPath.item == 1
      {
          let myCell = collectionView.dequeueReusableCell(withReuseIdentifier: "PestañaUno", for: indexPath) as! PestañaUno
      }
  
      return myCell
  }
  </code></pre>