Swift different images for Annotation

问题:

I managed to get a custom icon for a annotation pin in Swift, but now I am still stuck using 2 different images for different annotations. Right now a button adds a annotation to the map. There should be another button that also adds a annotation but with another icon.

Is there a way to use the reuseId for this?

class ViewController: UIViewController, MKMapViewDelegate {

@IBOutlet weak var Map: MKMapView!

@IBAction func btpressed(sender: AnyObject) {

    var lat:CLLocationDegrees = 40.748708
    var long:CLLocationDegrees = -73.985643
    var latDelta:CLLocationDegrees = 0.01
    var longDelta:CLLocationDegrees = 0.01

    var span:MKCoordinateSpan = MKCoordinateSpanMake(latDelta, longDelta)
    var location:CLLocationCoordinate2D = CLLocationCoordinate2DMake(lat, long)
    var region:MKCoordinateRegion = MKCoordinateRegionMake(location, span)

    Map.setRegion(region, animated: true)


    var information = MKPointAnnotation()
    information.coordinate = location
    information.title = "Test Title!"
    information.subtitle = "Subtitle"

    Map.addAnnotation(information)
}

func mapView(mapView: MKMapView!, viewForAnnotation annotation: MKAnnotation!) -> MKAnnotationView! {
    if !(annotation is MKPointAnnotation) {
        return nil
    }

    let reuseId = "test"

    var anView = mapView.dequeueReusableAnnotationViewWithIdentifier(reuseId)
    if anView == nil {
        anView = MKAnnotationView(annotation: annotation, reuseIdentifier: reuseId)
        anView.image = UIImage(named:"1.png")
        anView.canShowCallout = true
    }
    else {
        anView.annotation = annotation
    }

    return anView
}

回答1:

In the viewForAnnotation delegate method, set the image based on which annotation the method is being called for.

Be sure to do this after the view is dequeued or created (and not only in the if anView == nil part). Otherwise, annotations that use a dequeued view will show the image of the annotation that used the view previously.

With the basic MKPointAnnotation, one crude way to tell annotations apart is by their title but that's not very flexible.

A better approach is to use a custom annotation class that implements the MKAnnotation protocol (an easy way to do that is to subclass MKPointAnnotation) and add whatever properties are needed to help implement the custom logic.

In the custom class, add a property, say imageName, which you can use to customize the image based on the annotation.

This example subclasses MKPointAnnotation:

class CustomPointAnnotation: MKPointAnnotation {
    var imageName: String!
}

Create annotations of type CustomPointAnnotation and set their imageName:

var info1 = CustomPointAnnotation()
info1.coordinate = CLLocationCoordinate2DMake(42, -84)
info1.title = "Info1"
info1.subtitle = "Subtitle"
info1.imageName = "1.png"

var info2 = CustomPointAnnotation()
info2.coordinate = CLLocationCoordinate2DMake(32, -95)
info2.title = "Info2"
info2.subtitle = "Subtitle"
info2.imageName = "2.png"

In viewForAnnotation, use the imageName property to set the view's image:

func mapView(mapView: MKMapView!, viewForAnnotation annotation: MKAnnotation!) -> MKAnnotationView! {
    if !(annotation is CustomPointAnnotation) {
        return nil
    }

    let reuseId = "test"

    var anView = mapView.dequeueReusableAnnotationViewWithIdentifier(reuseId)
    if anView == nil {
        anView = MKAnnotationView(annotation: annotation, reuseIdentifier: reuseId)
        anView.canShowCallout = true
    }
    else {
        anView.annotation = annotation
    }

    //Set annotation-specific properties **AFTER**
    //the view is dequeued or created...

    let cpa = annotation as CustomPointAnnotation
    anView.image = UIImage(named:cpa.imageName)

    return anView
}

回答2:

iOS Swift Code With Help of Anna and Fabian Boulegue:

import UIKit
import MapKit

class ViewController: UIViewController, MKMapViewDelegate {

    @IBOutlet weak var mapView: MKMapView!

    override func viewDidLoad() {
        super.viewDidLoad()

        self.mapView.delegate = self

        var info1 = CustomPointAnnotation()
        info1.coordinate = CLLocationCoordinate2DMake(26.889281, 75.836042)
        info1.title = "Info1"
        info1.subtitle = "Subtitle"
        info1.imageName = "flag.png"

        var info2 = CustomPointAnnotation()
        info2.coordinate = CLLocationCoordinate2DMake(26.862280, 75.815098)
        info2.title = "Info2"
        info2.subtitle = "Subtitle"
        info2.imageName = "flag.png"

        mapView.addAnnotation(info1)
        mapView.addAnnotation(info2)
    }

    func mapView(mapView: MKMapView!, viewForAnnotation annotation: MKAnnotation!) -> MKAnnotationView! {

        println("delegate called")

        if !(annotation is CustomPointAnnotation) {
            return nil
        }

        let reuseId = "test"

        var anView = mapView.dequeueReusableAnnotationViewWithIdentifier(reuseId)
        if anView == nil {
            anView = MKAnnotationView(annotation: annotation, reuseIdentifier: reuseId)
            anView.canShowCallout = true
        }
        else {
            anView.annotation = annotation
        }

        //Set annotation-specific properties **AFTER**
        //the view is dequeued or created...

        let cpa = annotation as CustomPointAnnotation
        anView.image = UIImage(named:cpa.imageName)

        return anView
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
}

class CustomPointAnnotation: MKPointAnnotation {
    var imageName: String!
}