对于应该是一段非常简单的代码，我有几个问题。目标是从数据库中读取项目并将它们固定在 map 上。如果项目已被标记为收藏夹，图钉应该是不同的颜色。

第一个问题是不是所有的项目都被渲染。在示例中，我将使用查询返回的 12 个结果，并且我已验证每个项目都创建了一个 MKAnnotation，并且每个注释都调用了 ViewFor。

除了不显示所有引脚外，还有另外两个问题。

滚动 map 时，第一个 Pin 图会随机丢失其标题。

其次最喜欢的(绿色)很少呈现绿色。 80% 的时间它以标准蓝色出现。我再次确认 MKMarkerAnnotationView 颜色设置正确。

鉴于所有这些问题，我不得不得出结论，我在做一些根本上非常错误的事情。这很奇怪，因为这看起来非常简单。

class FacilityMarker: NSObject, MKAnnotation {

// title and subtitle are from the MKAnnotation protocol
var coordinate:     CLLocationCoordinate2D
var title:          String?
var address:        String
var phone:          String
var providerNumber: String
var favorite:       Bool
var subtitle:       String? {
    get {
        return phone
    }
}

View Controller

    class MapViewController: UIViewController, CLLocationManagerDelegate, MKMapViewDelegate {

@IBOutlet weak var mapView: MKMapView!

override func viewDidLoad() {
    super.viewDidLoad()
    mapView.delegate = self
    mapView.showAnnotations(mapView.annotations, animated: true)


// Create Annotations for all the facilities that are now visible on map
func mapView(_ mapView: MKMapView, regionDidChangeAnimated animated: Bool) {
    let edgePoints = mapView.edgePoints()

    let minLat = edgePoints.ne.latitude < edgePoints.sw.latitude ? edgePoints.ne.latitude : edgePoints.sw.latitude
    let maxLat = edgePoints.ne.latitude > edgePoints.sw.latitude ? edgePoints.ne.latitude : edgePoints.sw.latitude
    let minLong = edgePoints.ne.longitude < edgePoints.sw.longitude ? edgePoints.ne.longitude : edgePoints.sw.longitude
    let maxLong = edgePoints.ne.longitude > edgePoints.sw.longitude ? edgePoints.ne.longitude : edgePoints.sw.longitude
    let visibleCitiesReqeuest =
        managedObjectModel.fetchRequestFromTemplate(withName: "FetchByCoordinates", substitutionVariables: ["minLat" : minLat, "minLong" : minLong, "maxLat" : maxLat, "maxLong" : maxLong])
    do {
        let facilities = try CoreDataHelper.shared.persistentContainer.viewContext.fetch(visibleCitiesReqeuest!) as! [FacilityMO]
       for facility in facilities {
            let facilityMarker = FacilityMarker(name: facility.facilityName!, address: facility.addressLine1!, location: facility.location!, phone: facility.phoneNumber!, providerNumber: facility.providerNumber!, favorite: facility.favorite)   
            mapView.addAnnotation(facilityMarker)
        }
    } catch {
        let alertController = UIAlertController(title: "No Facilities", message: "There are no Facilities within the visible map area", preferredStyle: .alert)
        alertController.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.cancel, handler: nil))
        self.present(alertController, animated: true, completion: nil)
    }
}

// Put the pins in the map
func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
    guard let annotation = annotation as? FacilityMarker else { return nil}

    let identifier = "facility"
    var view: MKMarkerAnnotationView
    if let dequeuedView = mapView.dequeueReusableAnnotationView(withIdentifier: identifier) as?
        MKMarkerAnnotationView {
        dequeuedView.annotation = annotation
        view = dequeuedView
    } else {
        print("CREATING NEW View for: \(annotation.title!)")
        view = MKMarkerAnnotationView(annotation: annotation, reuseIdentifier: identifier)
    }

    // Set the Colors
    if (annotation.favorite) {
        view.markerTintColor = .green
        view.tintColor = .green
    } else {
        view.markerTintColor = .blue
        view.tintColor = .blue
    }
    return view
}

这是查询返回的实际数据。只有突出显示的项目才会被渲染。 这在所有测试中都是 100% 一致的。

• CREATING NEW View for: SEMINOLE DIALYSIS CENTER

• 为以下项目创建新 View :塞米诺尔湖透析

• CREATING NEW View for: RAI CARE CENTERS - LARGO

• CREATING NEW View for: BAY BREEZE DIALYSIS CLINIC INC

• 为 CLEARWATER, LLC 的 RENVIVA 透析中心创建新 View

• CREATING NEW View for: FKC - BELLEAIR DIALYSIS CENTER

• CREATING NEW View for: RAI CARE CENTERS - CLEARWATER

• 为 FMC - BELLEAIR HOME THERAPIES 创造新视野

• CREATING NEW View for: CORVA GULF COAST DIALYSIS CENTER

• 为 GULF BREEZE 透析中心创建新 View

• CREATING NEW View for: BMA - CLEARWATER

• 为 RAI-US 19 NORTH-CLEARWATER 创建新 View

以下是显示上述结果的截图

这是一个初始渲染。这次 BMA 引脚是蓝色的，它被设置为绿色。

这次滚动后 BMA 色调是正确的。没有什么时候是正确的模式。

更多的滚动只是为了增加更多的奇怪性，有时一个或多个注释不会呈现它们的标题属性

请求调试的输出:

• RAI CARE CENTERS - LARGO 是蓝色的
• BMA - CLEARWATER 是绿色的
• RENVIVA DIALYSIS CENTER OF CLEARWATER, LLC 是蓝色的
• RAI 护理中心 - CLEARWATER 是蓝色的
• FKC - BELLEAIR 透析中心是蓝色的
• FMC - BELLEAIR HOME THERAPIES 是蓝色的
• GULF BREEZE 透析中心是蓝色的
• BAY BREEZE DIALYSIS CLINIC INC 是蓝色的
• RAI-US 19 NORTH-CLEARWATER 是蓝色的
• CORVA GULF COAST DIALYSIS CENTER 是蓝色的

最佳答案

尝试以下调试代码。你能显示输出吗？

    ...
    // Set the Colors
    if (annotation.favorite) {
        print(annotation.title, "is green")
        view.markerTintColor = .green
        view.tintColor = .green
    } else {
        print(annotation.title, "is blue")
        view.markerTintColor = .blue
        view.tintColor = .blue
    }
    ...

关于ios - map 注释有很多问题，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/49532389/