Swift Mapkit Received memory warning

Question

Im developing ipad app and looking memory using good all viewcontrollers but my MapDetailViewController gives me Received memory warning how can i resolve it .

All viewcontrollers use my app max 34.MB memory but MapDetailViewController using 100 MB More. My codes under below what is wrong ?

import UIKit
import MapKit

class MapDetailViewController: UIViewController,MKMapViewDelegate  {

    @IBOutlet var mapView:MKMapView!
    @IBOutlet weak var mapArea: DesignableView!
    @IBOutlet weak var nameSales: DesignableLabel!


    var showmapListcomming = String()

    override func viewDidLoad() {
        super.viewDidLoad()

        // Show Map

        let myString: String = showmapListcomming
        var myStringArr = myString.componentsSeparatedByString(",")

        nameSales.text = myStringArr[0]

        let annotation = MKPointAnnotation()
        let latitude:CLLocationDegrees = (myStringArr[1] as NSString).doubleValue
        let longitude:CLLocationDegrees = (myStringArr[2] as NSString).doubleValue
        let latDelta:CLLocationDegrees = 150
        let lonDelta:CLLocationDegrees = 150
        let span:MKCoordinateSpan = MKCoordinateSpanMake(latDelta, lonDelta)
        let location:CLLocationCoordinate2D = CLLocationCoordinate2DMake(latitude, longitude)
        let region:MKCoordinateRegion = MKCoordinateRegionMake(location, span)

        mapView.setRegion(region, animated: false)

        annotation.coordinate = location
        annotation.title = myStringArr[0]
        annotation.subtitle = "User"
        mapView.addAnnotation(annotation)

 }

    // MARK: - MKMapViewDelegate methods

    func mapView(mapView: MKMapView, viewForAnnotation annotation: MKAnnotation) -> MKAnnotationView? {

        let annotationView = MKPinAnnotationView()
        return annotationView
    }

    override func viewWillAppear(animated: Bool) {
        super.viewWillAppear(animated)
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
}

}