Jacob King Jacob King - 2 months ago 14
Swift Question

iOS MapKit - Detect when map is fully zoomed in?

So I am using a clustering library to group annotations and there is a small bug with it whereby some very close together annotations can appear grouped when the map is fully zoomed in. With this being a framework I can't do much about it directly but I can disable all grouping if the map is fully zoomed in. The problem is I can't work out a reliable way of doing this.

Here is my

regionDidChangeAnimated
code which is ideally where I would like to check if the map is fully zoomed in (to the point where you cant zoom in any more).

func mapView(mapView: MKMapView, regionDidChangeAnimated animated: Bool) {
NSOperationQueue().addOperationWithBlock {
let scale: Double = Double(self.map.bounds.size.width) / self.map.visibleMapRect.size.width
let annotations = self.clusteringManager?.clusteredAnnotationsWithinMapRect(self.map.visibleMapRect, withZoomScale: scale)
self.clusteringManager?.displayAnnotations(annotations, onMapView: self.map)
}
}


I have tried inspecting the
mapView.region.span
property but I'm sure this will change depending on screen size etc...

Any suggestions? Thanks in advance.

Answer

You need to extend your MKMapView:

class YourMapView : MKMapView {

    // function returns current zoom level of the map

    func getCurrentZoom() -> Double {

        var angleCamera = self.camera.heading
        if angleCamera > 270 {
            angleCamera = 360 - angleCamera
        } else if angleCamera > 90 {
            angleCamera = fabs(angleCamera - 180)
        }

        let angleRad = M_PI * angleCamera / 180 

        let width = Double(self.frame.size.width)
        let height = Double(self.frame.size.height)

        let offset : Double = 20 // offset of Windows (StatusBar)
        let spanStraight = width * self.region.span.longitudeDelta / (width * cos(angleRad) + (height - offset) * sin(angleRad))
        return log2(360 * ((width / 256) / spanStraight)) + 1;
      }

}

Now your able to read out the current Zoom Level out in the following delegate methods:

regionDidChangeAnimated

And

regionWillChangeAnimated
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