用于多个注释的 MapKit 自定义图像

Question

我有新闻对象，想根据新闻类别自定义新闻标注。如果没有switch语句，如果我只写annotationView?.image = UIImage(named: "ic_sports")，所有注解；图片显示运动图像。如何获取该注释的新闻类别 ID，以便根据该 ID 更改注释图像？

控制台为所有注释打印 Log annotation is news。

新闻：

class News: NSObject, MKAnnotation {

    let coordinate: CLLocationCoordinate2D
    var categoryId: Int
    var title: String?

    // Other variables and init function ...

    func getCategoryId() -> Int {
        return categoryId
    }

}

地图视图控制器：

function parse(json: JSON) {
    // ...
    let news = News(categoryId: data["category_id"].intValue,
                    title: data["title"].stringValue,
                    coordinate: coordinate)
    self.mapView.addAnnotation(news)
}


func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {

    if annotation is News {
        print("Log annotation is news")
    } else {
        print("Log annotation NOT news")
    }

    var annotationView = mapView.dequeueReusableAnnotationView(withIdentifier: "newsAnnotationView")
    if annotationView == nil {
        annotationView = MKAnnotationView(annotation: annotation, reuseIdentifier: "newsAnnotationView")
    }
    switch(annotation.getCategoryId()) {
    case 1: // Other
        annotationView?.image = UIImage(named: "ic_other")
        break;
    case 2: // sports
        annotationView?.image = UIImage(named: "ic_sports")
        break;
    case 3: // education
        annotationView?.image = UIImage(named: "ic_education")
        break;
    case 4: // crime
        annotationView?.image = UIImage(named: "ic_crime")
        break;
    case 5: // health
        annotationView?.image = UIImage(named: "ic_health")
        break;
    default:
        break;
    }
    annotationView?.canShowCallout = true
    return annotationView
}

Answer 1

我已经解决了这个问题，方法是创建一个新闻对象并将 annotation 的值作为新闻赋予它，然后使用 news.getCategoryId()

func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {

    let news = annotation as! News

    var annotationView = mapView.dequeueReusableAnnotationView(withIdentifier: "newsAnnotationView")

    if annotationView == nil {
        annotationView = MKAnnotationView(annotation: news, reuseIdentifier: "newsAnnotationView")
    }

    switch(news.getCategoryId()) {
    case 1: // Other
        annotationView?.image = UIImage(named: "ic_other")
        break;
    case 2: // sports
        annotationView?.image = UIImage(named: "ic_sports")
        break;
    case 3: // education
        annotationView?.image = UIImage(named: "ic_education")
        break;
    case 4: // crime
        annotationView?.image = UIImage(named: "ic_crime")
        break;
    case 5: // health
        annotationView?.image = UIImage(named: "ic_health")
        break;
    default:
        break;
    }

    annotationView?.canShowCallout = true
    return annotationView
}

用于多个注释的 MapKit 自定义图像

MapKit custom image for multiple annotations

swift4

mapkitannotation