swift - 向 map View 添加注释时出错

Question

我有一个应用程序，在其中我从核心数据模型获取数据，然后我希望将其呈现在 map 上。当我向 map View 添加注释时，出现错误:无法将类型 'Swift._ContigouslyArrayStorage<>' () 的值转换为 'MKAnnotation' ()。同样的逻辑适用于 Swift 2，但显然不适用于 Swift 3。在哪里以及如何将注释添加到 map View 。代码是:

  override func viewDidAppear(_ animated: Bool) {

    var rainFallGauges = [RainFallGauge]()
    let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "RainFallGauge")

    do {
        rainFallGauges = try coreDataStack.context.fetch(fetchRequest) as! [RainFallGauge]

        obsCount = rainFallGauges.count
    } catch let error as NSError {
        print("Could not fetch \(error), \(error.userInfo)")
    }

    if obsCount == 0 {

        let alert = UIAlertController(title: "Sorry", message: "No gauges found", preferredStyle: UIAlertControllerStyle.alert)
        alert.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.default, handler: nil))
        self.present(alert, animated: true, completion: nil)
    } else {

        for rainFallGauge in rainFallGauges {

            resultsGauge = rainFallGauge.value(forKey: "gaugeName") as? String
            resultsLatitude = rainFallGauge.value(forKey: "gaugeLatitude") as? String
            resultsLongitude = rainFallGauge.value(forKey: "gaugeLongitude") as? String
            print(resultsGauge)

            if (resultsLatitude != nil && resultsLongitude != nil)  && (resultsLatitude?.isEmpty == false && resultsLongitude?.isEmpty == false) {
                let latNSString = NSString(string: resultsLatitude!)
                setLatitude = latNSString.doubleValue
                print(setLatitude)

                let longNSString = NSString(string: resultsLongitude!)
                setLongitude = longNSString.doubleValue
                print(setLongitude)

                self.gauges.append(Gauges(gaugeTitle: resultsGauge, latitude: setLatitude, longitude: setLongitude))
                print(gauges.count)
            } else if gauges.count == 0 {
                let alert = UIAlertController(title: "Sorry", message: "No gauges", preferredStyle: UIAlertControllerStyle.alert)
                alert.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.default, handler: nil))
                self.present(alert, animated: true, completion: nil)
            }
        }
    }

    self.gaugeMap.delegate = self
    self.gaugeMap.addAnnotation(self.gauges as! MKAnnotation)

    gaugeMap.mapType = .hybrid

    let rectToDisplay = self.gauges.reduce(MKMapRectNull) {
        (mapRect: MKMapRect, gauge: Gauges) -> MKMapRect in
        let placePointRect = MKMapRect(origin: gauge.location.mapPoint, size: MKMapSize(width: 0, height: 0))

        return MKMapRectUnion(mapRect, placePointRect)
    }

我将上面的数组“gauges”声明为:

    var gauges = [Gauges]()

并创建了类标尺来保存注释的相关信息。

任何能够指导我了解 addAnnotation 语句的正确语法及其位置的建议将不胜感激。

Answer 1

感谢您的见解。我误读了旧应用程序中的这一行，实际上是:

self.speciesMap.addAnnotations(self.places)

我通过简化并解决了我的问题:

for rainFallGauge in rainFallGauges {

            resultsGauge = rainFallGauge.value(forKey: "gaugeName") as? String
            resultsLatitude = rainFallGauge.value(forKey: "gaugeLatitude") as? String
            resultsLongitude = rainFallGauge.value(forKey: "gaugeLongitude") as? String
            print(resultsGauge)

            if (resultsLatitude != nil && resultsLongitude != nil)  && (resultsLatitude?.isEmpty == false && resultsLongitude?.isEmpty == false) {
                let latNSString = NSString(string: resultsLatitude!)
                setLatitude = latNSString.doubleValue
                print(setLatitude)

                let longNSString = NSString(string: resultsLongitude!)
                setLongitude = longNSString.doubleValue
                print(setLongitude)

                gaugeMap.addAnnotation(OneGauge(title: resultsGauge, subtitle: "", coordinate: CLLocationCoordinate2D(latitude: setLatitude, longitude: setLongitude)))

            }
        }
    }
    gaugeMap.mapType = .hybrid