为什么不调用ViewForAnnotation？

Question

我知道这个问题已被多次询问,但所有答案似乎与我的应用程序中发生的情况略有不同.

我的理解是,一旦mapView将其委托设置为显示它的ViewController,就会调用viewForAnnotation函数.当mapView滚动时,会在地图中添加注释,以便在mapView区域内显示.

目前我有一个主viewController(mainVC),它包含一个MKMapView(mapView)这个viewController控制四个不同的地图在mapView中显示.

func moveViews(sender:Int) {
    // This function handles which button on the Segmented Control was clicked and the loads the appropriate map into the mapView (passed as a para

    removeAnnotationsAndOverlays() // ~~~
    if sender == 0 {
        // First Map was selected
        let map1VC = map1VC()
        map1VC.loadMap1View(mapView)
        map1VC.centerMapOnLocation()
    }
    else if sender == 1 {
        // Second Map was selected
        let map2VC = map2VC()
        map2VC.loadMap2View(mapView)
    }
    else if sender == 2 {
        // Third Map was selected
        let map3VC = map3VC()
        map3VC.loadMap3View(mapView)
    }
    else if sender == 3 {
        // Fourth Map was selected
        let map4VC = map4VC()
        map4VC.loadMap4View(mapView)
    }
    else {
        // Load First Map as default
        let map1VC = map1VC()
        map1VC.loadMap1View(mapView)
        map1VC.centerMapOnLocation()
    }
}

有几个不同的类控制每个不同映射的功能:

1. 地图1 - 显示从plist读取的MKPolylines和自定义注释(继承自MKAnnotation)的组合 - 这非常有用!
2. 地图2 - 显示从plist读取的几个MKPolylines - 这非常有用!
3. 地图3 - 显示从plist读取的几个MKPolylines - 这非常有用!
4. 地图4 - 应显示多个自定义注释 - 这不起作用!

以下是Map 4发生的情况:

• MKMapView正在正确加载

  var mapView: MKMapView = MKMapView() // declared as a global variable/object inside the map4VC()
  
  // Initial function to set up Map
  //      Think of this function as the "override func viewDidLoad() {}"
  func loadMap4View(mV: MKMapView) {
  
  // This connects the parameter passed (mV) and sets it as the delegate for the mapView used throughout this file
  //      In other words, it allows the mapView on the MainVC to use all of the code in this file to handle different actions
  mapView = mV
  mapView.delegate = self
  
  let initialLocation = CLLocation(latitude: 50.3603125, longitude: 2.794017)
  
  // calculates the region you'll look at on the screen 
  let coordinateRegion = MKCoordinateRegionMakeWithDistance(initialLocation.coordinate, regionRadius, regionRadius)
  
  // sets the region of the map
  mapView.setRegion(coordinateRegion, animated: true)
  
  
  //addPins()  // This can use a custom function to load all of the Pins
  //mapView.addAnnotations(coords.allLocations!) // This line also works to add all of the individual pins
  
  mapView.addAnnotation(coords.allLocations![2]) // This adds one single Pin
  

  }

• 将mapView的委托设置为当前类(mapView.delegate = self)

• 它放大适当的位置(mapView.setRegion(coordinateRegion,animated:true))

• 该类从plist读取并(使用辅助类)构建一个自定义MKAnnotations数组(CemAnno)

• 这些位置存储在一个名为allLocations的CemAnno数组中:

  var allLocations: [CemAnno]? = [] // This is declared in the helper class along with a bunch of other stuff that grabs all of the information from a plist
  
   class CemAnno: NSObject, MKAnnotation {
  
  var coordinate: CLLocationCoordinate2D
  var title: String?
  var casualties: String?
  var visitInfo: String?
  var histInfo: String?
  var region: String?
  
  
  init(title: String, coordinate: CLLocationCoordinate2D, region: String, casualties: String, visitInfo: String, histInfo: String) {
  
  self.coordinate = coordinate
  self.title = title
  self.region = region
  self.casualties = casualties
  self.visitInfo = visitInfo
  self.histInfo = histInfo
  }
  

  }

  // This builds an object inside the the map4VC() class called coords that holds all of the information collected from the plist
  var coords = BuildCoordinates(filename: "Coordinate")
  

• 将这些中的每一个添加到地图(mapView.addAnnotations)并将它们显示为引脚(它们正在显示)mapView.addAnnotation(coords.allLocations![2])//这会添加一个单独的Pin Annotation(可以工作)但是从不调用viewForAnnotation函数

但是,这是有效的,我正在尝试自定义正在显示的注释,但ViewForAnnotation函数永远不会被调用????

// This function is NEVER called
func mapView(mapView: MKMapView, viewForAnnotation annotation: MKAnnotation) -> MKAnnotationView?
{
    // Define a reuse identifier. This is a string that will be used to ensure we reuse annotation views as much as possible.
    let identifier = "CemAnno"

    // Check whether the annotation we're creating a view for is one of our CemAnno objects.
    if annotation.isKindOfClass(CemAnno.self) {
        print("correct class")
        //let anno = annotation as! CustomAnnotation
        // Try to dequeue an annotation view from the map view's pool of unused views.
        var annotationView = mapView.dequeueReusableAnnotationViewWithIdentifier(identifier)

        if annotationView == nil {
            print("no reusable view")
            // If it isn't able to find a reusable view, create a new one using MKPinAnnotationView and sets its canShowCallout property to be true. This triggers the popup with the name.
            annotationView = MKPinAnnotationView(annotation: annotation, reuseIdentifier: identifier)
            annotationView!.canShowCallout = true

            // Create a new UIButton using the built-in .Custom type. This is so we can add an image to the button.
            let btn = UIButton(type: .DetailDisclosure)
            //btn.setImage(anno.image, forState: .Normal)
            annotationView!.rightCalloutAccessoryView = btn
        } else {
            print("reusing a view")
            // If it can reuse a view, update that view to use a different annotation.
            annotationView!.annotation = annotation
        }

        return annotationView

    }

    // If the annotation isn't from a CustomClass, it must return nil so iOS uses a default view.
    return MKPinAnnotationView()
}

我已经尝试在地图的当前视图区域内添加引脚的位置,但从不触发ViewForAnnotation.我已经尝试在地图的当前视图区域之外添加引脚的位置,但ViewForAnnotation永远不会被触发 - 我认为这应该是有效的,并且当我'滚动'地图并且它显示在内部应该触发该功能的当前视图区域,但它不会(我应该注意该引脚正在显示并显示在地图上).

这使我无法自定义我想要做的引脚.

我使用与Map 1完全相同的技术,但由于某种原因,ViewForAnnotation永远不会在Map 4中调用.

任何建议将不胜感激!!

Answer 1

我不时遇到这个问题.我发现有时你需要showAnnotations:animated:像这样手动调用 :

mapView.showAnnotations(mapView.annotations, animated: true)

Answer 2

抱歉,我看不到你的视图控制器mainVC的声明:你的控制器实现了MKMapViewDelegate？

import MapKit

class mainVC: UIViewController, MKMapViewDelegate 
{
    ...
} 

编辑1:如果代理人与您的控制器链接,请检查您的故事板上的视图控制器是否:

只需右键单击mapView即可.