swift - 自定义 MKAnnotation 字典输入 (CLLocationCooperative2d)

Question

import MapKit
import UIKit

class Point: NSObject, MKAnnotation {
    var id: String?
    var title: String?
    var coordinate: CLLocationCoordinate2D
    var subtitle: String?



    init(id: String, dictionary: Dictionary<String, AnyObject>){


        self.id = id

        if let title = dictionary["title"] as? String {
            self.title = title
        }

        if let subtitle = dictionary["subtitle"] as? String {
            self.subtitle = subtitle
        }

        if let coords = dictionary["coordinates"] as? [String:[String:Double]] {
            var latitude = coords.values.first!["latitude"]!
            var longitude = coords.values.first!["longitude"]!
            var location = CLLocationCoordinate2D(latitude: latitude, longitude: longitude)
            self.coordinate = location
        }

    }

错误:在隐式生成的 super.init 调用中未初始化属性 self.coordinate。

知道如何解决这个问题吗？

感谢您的一些建议。

Answer 1

您应该在其他情况下分配默认值

if let coords = dictionary["coordinates"] as? [String:[String:Double]] {
...
} else {
self.coordinate = <assign a default location>
}

或者

如果没有坐标，则不应创建对象。所以让你的 init 成为可选的。

 init?(id: String, dictionary: Dictionary<String, AnyObject>){

      if let coords = dictionary["coordinates"] as? [String:[String:Double]] {
           self.id = id

           if let title = dictionary["title"] as? String {
                self.title = title
           }

           if let subtitle = dictionary["subtitle"] as? String {
                self.subtitle = subtitle
           }
           var latitude = coords.values.first!["latitude"]!
           var longitude = coords.values.first!["longitude"]!
           var location = CLLocationCoordinate2D(latitude: latitude, longitude: longitude)
           self.coordinate = location
      } else {
           return nil
      }
 }