Access Attributes for Sub-Layer Within AGSDynamicMapServiceLayer

[dpmarley]

I'm fairly new to the iOS SDK and trying to work through some basic concepts here. What is the best way to access the attributes (the "attribute table" in old-school GIS terminology) associated with a sub-layer within an AGSDynamicMapServiceLayer? I am working on an iPad app with a standard split view (map on the right, in detail view; table in left column of split view) where I want to show a set of project locations on the map, and have those projects show as a list in the table on the left. Ultimately I want to have interaction between the map and the table (touch a row in table to zoom to location on map, etc.). I have the project locations in a feature class, and have that published as a standard AGS Map service. I have the service/layer loaded into the map as a AGSDynamicMapServiceLayer.

From the documentation, I can see that the AGSGraphic contains an attributes collection, but from the doc it appears I need to run an AGSQueryTask or other task in order to get an AGSFeatureSet containing the graphics/attributes. Is there a way to get it directly from the AGSDynamicMapServiceLayer that is already in the map?

So I could run a query to return all my records (say with a dummy where clause like "1=1") but this seems like an unnecessary step given that I already have the points on my map. And if I use a query result to display a graphics layer, then I lose the symbology associated with the layer itself, and have to utilize a client-side graphic to display the points. This might be OK, but just doesn't seem right when I am wanting to show a feature class in its entirety.

What's the best/recommended approach here?

Thanks in advance,

Dave

[nrjarecha]

The AGSDynamicMapServiceLayer you see in a map is nothing but an image of the map. So you cannot get attributes of the features from an image. Hence, you have to execute a query task to get the features as graphics.

Based on your description the best recommended approach would be to load all layers as AGSFeatureLayer and you'll get all graphics in a map with attributes and symbology defined in the service.

Hope this helps!

Regards,
Nimesh

[dpmarley]

Thanks for the clarification Nimesh. I had come to the same conclusion about the AGSDynamicMapServiceLayer and have been trying the Query approach - it seems like I can do what I need using query. The idea of using an AGSFeatureLayer is a good one...I will definitely explore that as well.

Thanks,

Dave