更新坐标时MapKit标记的标题不移动

Question

当我更新注释坐标时，只有标记在移动，标题停留在先前的位置，这是我更新坐标的部分：

for annotation in self.mapView.annotations
{
    if let ann = annotation as? Artwork
    {
        if user.id == ann.id
        {
           if ann.coordinate.latitude != user.latitude! && ann.coordinate.longitude != user.longitude!
           {
                let userCoordinates = CLLocationCoordinate2D(latitude: user.latitude!, longitude: user.longitude!)
                ann.coordinate = userCoordinates
           }                        
       }
    }
}

这是我的美术课：

import Foundation
import MapKit

class Artwork: NSObject, MKAnnotation
{
    let title: String?
    dynamic var coordinate: CLLocationCoordinate2D
    let id: Int

    init(title: String, coordinate: CLLocationCoordinate2D, id: Int)
    {
        self.title = title
        self.coordinate = coordinate
        self.id = id
        super.init()
    }    
}

有人对标题为何保留在先前位置有想法吗？

Answer 1

这是工作代码：

ann.title = username
ann.coordinate = userCoordinates

//And in the class I modified to this:
let id: Int
dynamic var title: String?
dynamic var coordinate: CLLocationCoordinate2D