設置註解MKMapView顯示錯誤的圖像

Question

設置註釋查看圖像我有以下代碼來設置引腳圖像基於陣列中的哪個對象被用來創建引腳。 問題是引腳沒有顯示引腳的正確圖像。

func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? { 
     let identifier = "MyPin" 

     if annotation is MKUserLocation { 
      return nil 
     } 

     var annotationView = mapView.dequeueReusableAnnotationView(withIdentifier: identifier) 

     if annotationView == nil { 
      annotationView = MKAnnotationView(annotation: annotation, reuseIdentifier: identifier) 
      annotationView?.canShowCallout = true 

      var selectedStation = fuel() 

      for station in fuelStations { 
       if (annotation.title! == station.Name){ 
        selectedStation = station 
       } 
      } 

      var imageName = "" 

      switch(selectedStation.Brand) { 
      case "MORRISONS" : 
       imageName = "fuel-morrisons" 
       break; 
      case "TEXACO" : 
       imageName = "fuel-texaco" 
       break; 
      case "SAINSBURY" : 
       imageName = "fuel-sainsbury" 
       break; 
      case "SHELL" : 
       imageName = "fuel-shell" 
       break; 
      case "BP" : 
       imageName = "fuel-bp" 
       break; 
      case "TESCO" : 
       imageName = "fuel-tesco" 
       break; 
      case "TESCO EXTRA" : 
       imageName = "fuel-tesco" 
       break; 
      case "ESSO" : 
       imageName = "fuel-esso" 
       break; 
      default : imageName = "NEWFuel" 
      } 

      print("selected station: " + selectedStation.Brand + " imagename: " + imageName) 

      let pinImage = UIImage(named: imageName) 

      let size = CGSize(width: 40, height: 45) 
      UIGraphicsBeginImageContext(size) 
      pinImage!.draw(in: CGRect(x:0, y:0, width:size.width, height:size.height)) 
      let resizedImage = UIGraphicsGetImageFromCurrentImageContext() 
      UIGraphicsEndImageContext() 

      annotationView?.image = resizedImage 

     } else { 
      annotationView?.annotation = annotation 
     } 

     return annotationView 
    } 

這些引腳與創建：

for station in self.fuelStations{ 
         let myAnnotation: MKPointAnnotation = MKPointAnnotation() 
         myAnnotation.coordinate = CLLocationCoordinate2DMake(station.lat, station.lng); 
         myAnnotation.title = station.Name 

         myAnnotation.subtitle = station.Brand 

         DispatchQueue.main.async { 
          self.mapView.addAnnotation(myAnnotation) 
         } 
        } 

的放出來的，應該正確工作的打印建議，錯誤的圖片怎麼過還是在錯誤的腳。

selected station: TOTAL imagename: NEWFuel 
selected station: TESCO EXTRA imagename: fuel-tesco 
selected station: BP imagename: fuel-bp 
selected station: ESSO imagename: fuel-esso 
selected station: GULF imagename: NEWFuel 
selected station: ESSO imagename: fuel-esso 
selected station: ESSO imagename: fuel-esso 
selected station: TESCO EXTRA imagename: fuel-tesco 
selected station: MURCO imagename: NEWFuel 
selected station: BP imagename: fuel-bp 
selected station: GULF imagename: NEWFuel 
selected station: JET imagename: NEWFuel 
selected station: ESSO imagename: fuel-esso 
selected station: GULF imagename: NEWFuel 
selected station: ASDA imagename: NEWFuel 
selected station: BP imagename: fuel-bp 
selected station: TESCO imagename: fuel-tesco 
selected station: JET imagename: NEWFuel 
selected station: SHELL imagename: fuel-shell 
selected station: ESSO imagename: fuel-esso 
selected station: ESSO imagename: fuel-esso 
selected station: SHELL imagename: fuel-shell 
selected station: ASDA imagename: NEWFuel 
selected station: SHELL imagename: fuel-shell 
selected station: BP imagename: fuel-bp 
selected station: ESSO imagename: fuel-esso 
selected station: ESSO imagename: fuel-esso 
selected station: TOTAL imagename: NEWFuel 

Answer 1

您的圖片，選擇邏輯是錯誤的（這是在錯誤的地方）。您需要執行的每個註釋的圖像選擇邏輯，而不僅僅是未被重用的新註釋。

這是你在做什麼：

if annotationView == nil { 
     // your image-choosing logic 
    } else { 
     annotationView?.annotation = annotation 
    } 

所以，如果您的註解視圖是一個重用註釋，你什麼都不做;你的邏輯從未被使用過。但這意味着你不能確定這裏的圖像。但有一個圖像：來自舊的重用註釋視圖的圖像。因此，這個註釋是錯誤的圖像。