topic visibleAreaEnvelope not set after zoom in ArcGIS Runtime SDK for iOS Questions

visibleAreaEnvelope not set after zoom

KatherineLawler — Mon, 28 Apr 2014 21:31:04 GMT

I'm trying to retrieve the visibleAreaEnvelope set after performing a zoom operation such as zoomToEnvelope or zoomToResolution etc. The following code performs the zoom as expected, however when I query the visibleAreaEnvelope it is always the envelope that was in existence before the zoom (in my case the max envelope).   Does the zoom have to finish before the new envelope is available? If so, I can't find any way to determine when the map has been fully updated.

e.g. //In this example centre has been set to the GPS location in WKID:102100 map units

        double zoomRes = [agsMapView minResolution];
        while (zoomRes < 2)
            zoomRes *= 2;
        AGSSpatialReference *srs = [AGSSpatialReference spatialReferenceWithWKID:102100];
        [agsMapView zoomToResolution:zoomRes withCenterPoint:[AGSPoint pointWithX:centre.x y:centre.y spatialReference:srs] animated:NO];
        AGSEnvelope *envelope1 = [webMapView.agsMapView visibleAreaEnvelope];

Re: visibleAreaEnvelope not set after zoom

NimeshJarecha — Tue, 29 Apr 2014 15:00:49 GMT

Yes, you'll have to wait for zoom to finish to fetch new visibleAreaEnvelope. You should listen to the AGSMapViewDidEndZoomingNotification (AGSMapView doc).

Hope this helps!

Regards,
Nimesh

Re: visibleAreaEnvelope not set after zoom

KatherineLawler — Wed, 30 Apr 2014 01:50:11 GMT

Thanks Nimesh,

I was hoping to avoid that but it does work. Since in my case I need to know right away I have to wait for it in a background thread which is a bit messy but does work. It would be nice if there were similar routines as there are for MapKit where you can query what the resulting limits will be given a new envelope before actually setting it.

Kathy