如何在Swift中实现GMUClusterRenderer

Question

我正在使用iOS的Google Maps
API，并想使用标记聚类实用程序。我想出了如何显示聚簇标记，但是我想自定义标记。有人可以解释如何设置/更改每个标记或群集标记的图标和标题吗？示例代码将非常有帮助。

class POIItem: NSObject, GMUClusterItem {
    var position: CLLocationCoordinate2D
    var name: String!

    init(position: CLLocationCoordinate2D, name: String) {
        self.position = position
        self.name = name
    }
}

class MyRenderer: NSObject, GMUClusterRenderer {
    var mapView: GMSMapView
    var clusterIconGenerator: GMUClusterIconGenerator
    var clusterManager: GMUClusterManager

    init(mapView: GMSMapView, clusterIconGenerator: GMUClusterIconGenerator, clusterManager: GMUClusterManager) {
        self.mapView = mapView
        self.clusterIconGenerator = clusterIconGenerator
        self.clusterManager = clusterManager
    }

    func renderClusters(clusters: [GMUCluster]) {

    }

    func update() {

    }
}

到目前为止，这就是我所拥有的。我不知道该如何处理renderClusters和更新函数。

Answer 1

在 Swift 4上 ，我找到了一种针对聚簇标记的干净解决方案，可以为聚簇使用自定义图像，并在其中包含聚簇数：

class MapClusterIconGenerator: GMUDefaultClusterIconGenerator {

    override func icon(forSize size: UInt) -> UIImage {
        let image = textToImage(drawText: String(size) as NSString,
                                inImage: UIImage(named: "cluster")!,
                                font: UIFont.systemFont(ofSize: 12))
        return image
    }

    private func textToImage(drawText text: NSString, inImage image: UIImage, font: UIFont) -> UIImage {

        UIGraphicsBeginImageContext(image.size)
        image.draw(in: CGRect(x: 0, y: 0, width: image.size.width, height: image.size.height))

        let textStyle = NSMutableParagraphStyle()
        textStyle.alignment = NSTextAlignment.center
        let textColor = UIColor.black
        let attributes=[
            NSAttributedStringKey.font: font,
            NSAttributedStringKey.paragraphStyle: textStyle,
            NSAttributedStringKey.foregroundColor: textColor]

        // vertically center (depending on font)
        let textH = font.lineHeight
        let textY = (image.size.height-textH)/2
        let textRect = CGRect(x: 0, y: textY, width: image.size.width, height: textH)
        text.draw(in: textRect.integral, withAttributes: attributes)
        let result = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return result!
    }

}

比集群管理器的设置：

private func setupClustering() {
    guard let mapView = self.mapView else { return }

    let iconGenerator = MapClusterIconGenerator()
    let renderer = MapClusterRenderer(mapView: mapView, clusterIconGenerator: iconGenerator)
    let algorithm = GMUNonHierarchicalDistanceBasedAlgorithm()
    clusterManager = GMUClusterManager(map: mapView, algorithm: algorithm, renderer: renderer)
}

我还使用了自定义群集渲染器MapClusterRenderer。