Question

以下是CCHMapClusterController的代码。我试图将此函数重写为Swift，但我不断收到此错误：

“初始化之前使用的变量注释”

就行了： clusterAnnotation = annotation

我对目标C没有任何线索，有人可以检查我是否正确地完成了最后几行吗？

目标C：

- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:    (id<MKAnnotation>)annotation
{
    MKAnnotationView *annotationView;

    if ([annotation isKindOfClass:CCHMapClusterAnnotation.class]) {
    static NSString *identifier = @"clusterAnnotation";

    ClusterAnnotationView *clusterAnnotationView = (ClusterAnnotationView *)[mapView dequeueReusableAnnotationViewWithIdentifier:identifier];
    if (clusterAnnotationView) {
        clusterAnnotationView.annotation = annotation;
    } else {
        clusterAnnotationView = [[ClusterAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:identifier];
        clusterAnnotationView.canShowCallout = YES;
    }

    CCHMapClusterAnnotation *clusterAnnotation = (CCHMapClusterAnnotation *)annotation;
    clusterAnnotationView.count = clusterAnnotation.annotations.count;
    clusterAnnotationView.blue = (clusterAnnotation.mapClusterController == self.mapClusterControllerBlue);
    clusterAnnotationView.uniqueLocation = clusterAnnotation.isUniqueLocation;
    annotationView = clusterAnnotationView;
}

return annotationView;
}

Swift Code：

func mapView(mapView: MKMapView!, viewForAnnotation annotation: MKAnnotation!) -> MKAnnotationView! {
    if annotation is MKUserLocation {
        // return nil so map view draws "blue dot" for standard user location
        return nil
    }

    var annotationView : MKAnnotationView?


    if annotation is CCHMapClusterAnnotation {
      //  let a : clusterAnnotationView = annotation as clusterAnnotationView

        let identifier: NSString = "clusterAnnotation"
        var clusterAnnotationView = (mapView.dequeueReusableAnnotationViewWithIdentifier(identifier as String)) as? ClusterAnnotationView!

        if (clusterAnnotationView != nil) {
            clusterAnnotationView!.annotation = annotation
        } else {
            clusterAnnotationView = ClusterAnnotationView(annotation: annotation, reuseIdentifier: "clusterAnnotation")
            clusterAnnotationView!.canShowCallout = true
        }

        var clusterAnnotation : CCHMapClusterAnnotation;
        var annotation : CCHMapClusterAnnotation
        clusterAnnotation = annotation
        clusterAnnotationView.count = clusterAnnotation.annotations.count
        clusterAnnotationView!.blue = (clusterAnnotation.mapClusterController == self.mapClusterControllerBlue);
        clusterAnnotationView!.uniqueLocation = clusterAnnotation.isUniqueLocation();
        annotationView = clusterAnnotationView

    }

Answer 1

使用这些行：

var clusterAnnotation : CCHMapClusterAnnotation;
var annotation : CCHMapClusterAnnotation
clusterAnnotation = annotation

声明了两个变量但未初始化，因此您会收到该警告。

此外，它还声明了一个与现有annotation参数同名的新本地变量annotation。您可能也会收到警告或错误。

如果您正在尝试转换此Objective-C行：

CCHMapClusterAnnotation *clusterAnnotation = 
    (CCHMapClusterAnnotation *)annotation;

投射 annotation参数为CCHMapClusterAnnotation，然后可能的Swift版本为：

let clusterAnnotation = annotation as? CCHMapClusterAnnotation

但是，您也可以将上面的注释类检查（if annotation is ...）与此类转换组合结合使用：

if let clusterAnnotation = annotation as? CCHMapClusterAnnotation {
    ...
}

初始化之前使用的变量注释

1 个答案: