CLLocationManager，核心數據和陣列

Question

我已經有了這個功能，並且非常接近它的工作原理！我想我有一個轉換問題。我可以將座標轉換爲具有3個屬性lat（Double），long（Double）和time（Date）的實體。這有效，我可以將內容打印到屏幕上，而且看起來不錯。但是當我嘗試提取並在地圖上使用座標時，它不起作用。我認爲這是因爲他們沒有被認爲是真正的座標。有任何想法嗎？

func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) 
    { 
     //ARRAY for lat/long data 
     var latArr:[Double] = [] 
     var longArr:[Double] = [] 
     var timeArr:[Date] = [] 

     let location = locations[0] 
     let annotation = MKPointAnnotation() 
     let span:MKCoordinateSpan = MKCoordinateSpanMake(0.01, 0.01) 
     let myLocation = CLLocationCoordinate2D(latitude: location.coordinate.latitude, longitude: location.coordinate.longitude) 
     //annotation.coordinate = myLocation 
     //annotation.title = "\(location.timestamp)" 
     //self.mapView.addAnnotation(annotation) 
     let region:MKCoordinateRegion = MKCoordinateRegionMake(myLocation, span) 
     self.mapView.setRegion(region, animated: true) 
     self.mapView.showsUserLocation = false //SET THIS 
     latitude.text = "latitude: " + "\(location.coordinate.latitude)" 
     longitude.text = "longitude: " + "\(location.coordinate.longitude)" 
     altitude.text = "altitude: " + "\(location.altitude)" 
     speed.text = "speed: " + "\(location.speed)" 
     timestamp.text = "timestamp: " + "\(location.timestamp)" 

     //START -- Core Data 
     let appDelegate = UIApplication.shared.delegate as! AppDelegate 
     let context = appDelegate.persistentContainer.viewContext 

     let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Data") 
     request.returnsObjectsAsFaults = false 

     let data = NSEntityDescription.insertNewObject(forEntityName: "Data", into: context) 
     //let data = NSNumber(double: self.location?.coordinate.latitude) 

     let dlat = Double("\(location.coordinate.latitude)") 
     let dlong = Double("\(location.coordinate.longitude)") 

     data.setValue(dlat, forKey: "lat") 
     data.setValue(dlong, forKey: "long") 
     data.setValue(location.timestamp, forKey: "time") 
     //END -- Core Data 

     do 
     { 
      try context.save() 
      //print("Saved") 
     } 
     catch 
     { 

     } 

     do 
     { 
      var lat: Double = 0 
      var long: Double = 0 
      let t = NSDate() 
      let results = try context.fetch(request) 

      if results.count > 0 
      { 
       for result in results as! [NSManagedObject] 
       { 
        if let datalat = result.value(forKey: "lat") as? Double 
        { 
         //latArr.append(datalat) 
         let lat = datalat 
         print(lat) 
        } 
        if let datalong = result.value(forKey: "long") as? Double 
        { 
         //longArr.append(datalong) 
         let long = datalong 
         print(long) 
        } 
        if let time = result.value(forKey: "time") as? Date 
        { 
         //timeArr.append(time) 
         let t = time 
         print(t) 
        } 
        let mLocation = CLLocationCoordinate2DMake(lat, long) 
        annotation.coordinate = mLocation 
        annotation.title = "\(t)" 
        self.mapView.addAnnotation(annotation) 
       } 
      } 
     } 
     catch 
     { 

     } 

Answer 1

我比你的代碼，我使用在類似的場景功能和合並的任何差異（和做了一些編輯爲簡潔起見，你可以採取或離開）。相關部分如下：

let request = NSFetchRequest<Data>(entityName: "Data") 
let annotations: [MKAnnotation] = [] 

annotation.title = 「\(t)」 

for result in results 
{ 
    if data.lat != nil && data.lon != nil 
    { 
     annotation.coordinate = CLLocationCoordinate2D(latitude: data.lat.doubleValue, longitude: data.lon.doubleValue) 
     annotations.append(annotation) 
    } 
    self.mapView.addAnnotations(annotations) 
    self.mapView.showAnnotations(annotations, animated: false) 
} 

我的代碼工作，但它是雨燕3.0這樣一些差異可能是由於從早期版本的變化，如果你使用2.2.or 2.3。我知道我需要將它從NSNumber（從CoreData）推送到Double，但是我認爲如果這是問題，你會得到一個編譯錯誤 - 不知道爲什麼你不是。正如我的評論中所提到的，如果航點僅僅在可見地圖區域外，則顯示註釋將有所幫助。

除此之外，你的代碼對我來說看起來還不錯 - 讓我知道它是否仍然存在。