ios - 如何为 MKPolygonRenderer 提供图像？

Question

我的代码正确获取图像并提供 map View 的边界。我想将图像放在边界内，但我不知道如何。我可以用颜色填充它，但我需要帮助使其成为图像。

func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {
    let renderer = MKPolygonRenderer(overlay: overlay)
    //renderer.fillColor = UIColor.red -> works
    return renderer
}

如何用我下载的图片填充它？ https://radar.weather.gov/ridge/Conus/RadarImg/latest_radaronly.gif

Answer 1

使用 MKOverlayRenderer 的子类，您将能够在实际 MKPolygon 上渲染 UIImage 叠加层

class CustomOverlayRenderer: MKOverlayRenderer  {

    private let overlayImage: UIImage?

    init(overlay: MKOverlay, image: UIImage? = nil) {
        self.overlayImage = image
        super.init(overlay: overlay)
    }

    override func draw(_ mapRect: MKMapRect, zoomScale: MKZoomScale, in context: CGContext) {
        guard let cgImage = self.overlayImage?.cgImage else { return }

        let rect = self.rect(for: overlay.boundingMapRect)

        context.scaleBy(x: 1.0, y: -1.0)
        context.translateBy(x: 0, y: -rect.height)
        context.draw(cgImage, in: rect)
    }

}

只需将您的委托(delegate)方法更改为使用 CustomOverlayRenderer，如下所示:

func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {
    return CustomOverlayRenderer(overlay: overlay, image: UIImage(named: "latest_radaronly.gif")!)
}