我如何用动画让我的引脚掉落在MKMapView上(可能比平常慢)

Question

我有一个代码，在MKMapView的可见部分显示10个自定义引脚:

func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
    if !(annotation is MKPointAnnotation) {
        return nil
    }
    var annotationView = mapView.dequeueReusableAnnotationView(withIdentifier: "demo")
    if annotationView == nil {
        annotationView = MKAnnotationView(annotation: annotation, reuseIdentifier: "demo")
        annotationView!.canShowCallout = true
    }
    else {
        annotationView!.annotation = annotation
    }
    annotationView!.image = UIImage(named: "OtherPin")
    return annotationView
} 

，生成随机引脚的函数为:

func addPinsToMap(mapView: MKMapView, amount howMany:Int) {
//First we need to calculate the corners of the map so we get the points
    let nePoint:CGPoint = CGPoint(mapView.bounds.origin.x + mapView.bounds.size.width, mapView.bounds.origin.y);
    let swPoint:CGPoint = CGPoint((mapView.bounds.origin.x), (mapView.bounds.origin.y + mapView.bounds.size.height));
//Then transform those point into lat,lng values
    let neCoord:CLLocationCoordinate2D = mapView.convert(nePoint, toCoordinateFrom: mapView)
    let swCoord:CLLocationCoordinate2D = mapView.convert(swPoint, toCoordinateFrom: mapView)
// Loop
for _ in 0 ..< howMany {
    let latRange:Double = Double(self.randomBetweenNumbers(firstNum: CGFloat(neCoord.latitude), secondNum: CGFloat(swCoord.latitude)))
    let longRange:Double = Double(self.randomBetweenNumbers(firstNum: CGFloat(neCoord.longitude), secondNum: CGFloat(swCoord.longitude)))
// Add new waypoint to map
    let location:CLLocationCoordinate2D = CLLocationCoordinate2DMake(latRange, longRange);
    let annotation = MKPointAnnotation()
    //let centerCoordinate = CLLocationCoordinate2D(latitude: 41, longitude:29)
    annotation.coordinate = location
    annotation.title = "Title"
    mapView.addAnnotation(annotation)
}//end
}//end

上面的代码，当用户打开地图，他看到大头针已经放置在一些随机的地方。我的问题是，我怎样才能让针一个接一个地掉下来，如果可能的话，我能让它们慢慢掉下来吗，这样每个针就会掉1-2秒，而不是立即移动?

Answer 1

有一个用于动画的注释animatesDrop属性你可以像这样设置它为真

annotationView!.canShowCallout = true
annotationView!.animatesDrop = true

检查这个