Class 从引脚映射方向

我正在创建一个标记应用程序，用户可以在地图上标记街道艺术。我希望用户能够点击pins（I）callout按钮并进入苹果地图

这个函数应该允许这种情况发生，但是我得到一个错误“实例成员‘坐标’不能用于类型‘艺术’”-

func openInMaps（）{

这是我的艺术课-

import Foundation
import FirebaseDatabase
import CoreLocation

class art {

let coordinate: CLLocationCoordinate2D!
var name: String!
var location: String!
var type: String!
var ref: FIRDatabaseReference?


init(snapshot: FIRDataSnapshot) {

    let snapshotValue = snapshot.value as! [String: Any]

    ref = snapshot.ref

    name = snapshotValue["name"] as! String

    location = snapshotValue["location"] as! String

    coordinate = CLLocationCoordinate2D(latitude: snapshotValue["lat"] as! Double, longitude: snapshotValue["lng"] as! Double)

   // type = snapshotValue["type"] as! String

}
}

如果有人能给我指出正确的方向，或者告诉我我做的是不是错了，那就太好了！谢谢

import Foundation
import FirebaseDatabase
import CoreLocation

class art {

let coordinate: CLLocationCoordinate2D!
var name: String!
var location: String!
var type: String!
var ref: FIRDatabaseReference?


init(snapshot: FIRDataSnapshot) {

    let snapshotValue = snapshot.value as! [String: Any]

    ref = snapshot.ref

    name = snapshotValue["name"] as! String

    location = snapshotValue["location"] as! String

    coordinate = CLLocationCoordinate2D(latitude: snapshotValue["lat"] as! Double, longitude: snapshotValue["lng"] as! Double)

   // type = snapshotValue["type"] as! String

}
}