How to animate Apple Mapkit flyover?

I watched a WWDC session on Apple Mapkit https://developer.apple.com/videos/play/wwdc2015/206/ I want to make a flyover animation showed at 31:33. Change camera angle from top to bottom and spin. But I wrote some code, it crushes. Please help me and tell me what's wrong with my code, thanks!

import UIKit
import CoreLocation
import MapKit

class Flyover: UIViewController, MKMapViewDelegate {
    var coordinate = CLLocationCoordinate2D(latitude: 40.7484405, longitude: -73.9856644)
    let distance : CLLocationDistance = 700
    let pitch : CGFloat = 65
    let heading = 90.0
    var camera: MKMapCamera?




    @IBOutlet var mapView: MKMapView!



    override func viewDidLoad() {
        super.viewDidLoad()
        mapView.mapType = .SatelliteFlyover
        let camera = MKMapCamera(lookingAtCenterCoordinate: coordinate,fromDistance: distance,pitch: pitch,heading: heading)
        mapView.camera = camera

        //I want the animation to play automatically as soon as the user is in the view.
        UIView.animateWithDuration(10.0, animations: {
            self.camera!.heading += 180
            self.camera!.pitch = 25
            self.mapView.camera = self.camera!
             })



    }

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



    /*
    // MARK: - Navigation

    // In a storyboard-based application, you will often want to do a little preparation before navigation
    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        // Get the new view controller using segue.destinationViewController.
        // Pass the selected object to the new view controller.
    }
    */

}