How to implement GMUClusterRenderer in Swift

Question

I am using Google Maps API for iOS and want to use marker clustering utility. I figured out how to show clustered markers, but I would like to customize markers. Can someone

Answer 1

I found a clean solution for clustered markers, on Swift 4, to use a custom image for the cluster with the number of cluster inside:

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!
    }

}

Than the setup for the cluster manager:

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)
}

I also used a custom cluster renderer MapClusterRenderer.