topic Re: AGSArcGISMapImageLayer and Identify in ArcGIS Runtime SDK for iOS Questions

AGSArcGISMapImageLayer and Identify

ToddAtkins — Mon, 16 Apr 2018 14:06:24 GMT

How does one execute an Identify task on an instance of AGSArcGISMapImageLayer? I've got a number of feature layers already on the map and running identifyLayersAtScreenPoint:tolerance:returnPopupsOnly:maximumResultsPerLayer:completion:() works as expected, but returns no results for the AGSArcGISMapImageLayer. In fact, the AGSArcGISMapImageLayer shows isPopupEnabled = false. The layer source is Tapestry Segmentation layer from: http://beitzanddaighgeo.maps.arcgis.com/home/item.html?id=eda0f20edc8448adaa3373cce237a57f and the layer is rendered correctly on the map.

Likely I'm missing something here, but how does one setup an AGSArcGISMapImageLayer so that it may be identified?

Thanks.

Re: AGSArcGISMapImageLayer and Identify

MarkDostal — Mon, 16 Apr 2018 15:36:59 GMT

Todd,

Than you for your question! The most likely scenario is that you are getting results, but they are located in the sublayerResults property of the AGSIdentifyLayerResult object passed to you from the identify completion handler.

Note that elements in the sublayerResults array property are also of type AGSIdentifyLayerResult, so they may have objects in their sublayerResults array as well.

If you are interested in only identifying layers in your AGSArcGISMapImageLayer, you can use one of the identify methods on AGSGeoView which takes a specific layer, like this one:

-(id<AGSCancelable>)identifyLayer:(AGSLayer*)layer
   screenPoint:(CGPoint)screenPoint
   tolerance:(double)tolerance
   returnPopupsOnly:(BOOL)returnPopupsOnly
   maximumResults:(NSInteger)maximumResults
   completion:(void(^)(AGSIdentifyLayerResult *identifyResult))completion;

If you are not finding your results in the sublayerResults array, let me know and we can dig into it further.

Mark

Re: AGSArcGISMapImageLayer and Identify

MarkDostal — Mon, 16 Apr 2018 16:50:08 GMT

I'm glad that works. Are you specifying "returnPopupsOnly == true" in your "Identify" operation? I'm not sure that makes a difference, but it would be good to know.

Also, when I load the layer into a ArcGIS.com map, I see there are three different county layers. All of them look like they have more attributes that what you're seeing, however. Make sure you have the correct one.

I couldn't find a way (yet) to programmatically specify which fields are returned for an Identify operation, but I will keep digging and keep you posted.

Mark

Re: AGSArcGISMapImageLayer and Identify

ToddAtkins — Mon, 16 Apr 2018 17:06:21 GMT

I'm creating my instance of of the layer using the portal id of the layer so I'm pretty sure it's only bringing over the right sublayers. I supposed I could sniff the requests through a proxy to be sure but I haven't done that yet.

Using returnPopupsOnly = false for my setup since I'm doing some custom stuff with the results.

I'm wondering if I can work around it by getting the objectid and firing off a query task to get the results I want but that seems super hackish (not to mention slower).

Thanks for your help. I'll keep digging too and post back if something comes up.

Re: AGSArcGISMapImageLayer and Identify

ToddAtkins — Mon, 16 Apr 2018 17:37:54 GMT

Followup:

I setup Charles proxy and watched the queries. They are being sent to the endpoint and executed properly and results are being returned that includes all the fields. But for some reason the API is stripping them down and only showing me the 8 fields I noted in the original post. I'm lost at this point.

Re: AGSArcGISMapImageLayer and Identify

MarkDostal — Mon, 16 Apr 2018 18:09:54 GMT

What is the type of the feature you are looking at the attributes for? If it is

AGSArcGISFeature, then try loading the feature and then looking at the attributes.

AGSArcGISFeature implements the AGSLoadable interface, so it's possible that not everything was downloaded yet.

In Swift, where f is the feature:

f.load { (error) in

//check attributes...

}

Let me know if that works,

Mark

Re: AGSArcGISMapImageLayer and Identify

ToddAtkins — Sun, 12 Dec 2021 15:59:29 GMT

It's an AGSGeoElement which I'm getting via identifyLayers(atScreenPoint:, tolerance:, returnPopupsOnly:, maximumResultsPerLayer:)

Relevant code where I tested the .load method:

for subLayerResult in result.sublayerResults {
   for subElement in subLayerResult.geoElements {
      guard let f = subElement as? AGSArcGISFeature else {
      return
   }
 
    f.load(completion: { (error) in
       guard error == nil else {
          print("Error")
          return
       }
       print("f", f.attributes)
   })
       print(subElement.attributes)
   }
}

Re: AGSArcGISMapImageLayer and Identify

MarkDostal — Mon, 16 Apr 2018 19:12:56 GMT

Todd,

Ok, thanks for the info. I'm still looking into a solution...

Mark

Re: AGSArcGISMapImageLayer and Identify

ToddAtkins — Mon, 16 Apr 2018 19:16:39 GMT

Some further findings:

I swapped out the service for the USA Flood Risk Layer (arcgis.com/home/item.html?id=6b09b1c163c740559dc31cce9144222e) and it's returning all the attributes and everything seems to be in order. (I'll track down some more map image services to test and see how they fare.)
Going back to the Demographics (arcgis.com/home/item.html?id=eda0f20edc8448adaa3373cce237a57f) results in only the same 8 attributes being returned. I noticed, however, that this only worked once. Any subsequent attempts to do an identify on the layer results in an application crash at ags_sqlite3_clear_bindings. Makes me wonder if the sheer number of fields in the demographics service is making the API choke? I'll be the first to admit I'm way out of my league when it comes to looking at this particular error.

Re: AGSArcGISMapImageLayer and Identify

MarkDostal — Mon, 16 Apr 2018 19:49:21 GMT

Todd,

Thanks for the additional information.

I will look into your crash and see if I can reproduce it. One thing to try would be to add the "All C++ Exceptions" breakpoint and see if it hits that breakpoint during the identify operation.

Mark

Re: AGSArcGISMapImageLayer and Identify

ToddAtkins — Mon, 16 Apr 2018 20:32:32 GMT

Thanks for your help, Mark. I set a breakpoint for All C++ Exceptions and it's not giving me any additional info than what I posted earlier--it's breaking at the same spot with the same exception.

Re: AGSArcGISMapImageLayer and Identify

MarkDostal — Mon, 16 Apr 2018 21:25:14 GMT

Todd,

I am able to reproduce the crash you reported and will pass it on to the appropriate people on the team. In the meantime, I will see if there are any possible work-arounds.

Thank you for your patience,

Mark

Re: AGSArcGISMapImageLayer and Identify

ToddAtkins — Mon, 16 Apr 2018 21:31:07 GMT

Mark, thank you very much for your time and help. I'm going to fiddle around with some ideas for a workaround on our end as well.

Re: AGSArcGISMapImageLayer and Identify

MarkDostal — Tue, 22 May 2018 16:14:26 GMT

Todd,

We've done some research on our end and found the issue is with the number of fields in the data. The limit in the Runtime SDK is 2,000 fields. The data you're using has more than that, which is causing the crash. We are in the process of fixing that crash for our next release, but the real solution for you would be to architect the data to have less than 2k fields.

Question: are you able to create and use hosted feature layers with your solution? If so, you can take a look at this documentation (Manage hosted feature layers—ArcGIS Online Help | ArcGIS ), which will explain how to create a "view" where you define what fields (among other things) you want in your data. This has the dual benefit only only bringing in the data you're interested in but also should be faster and prevent the crash.

If you're not able to use hosted feature layers, let me know.

Mark

Re: AGSArcGISMapImageLayer and Identify

ToddAtkins — Tue, 22 May 2018 16:38:29 GMT

Mark thanks for the follow up. Unfortunately we cannot create a feature

view for this layer since it is a Dynamic Map service and one of the Esri

Premium Living Atlas layers.

To work around the issue for now, we've created a service in our own AGOL

with the geometry and fields we're trying to use. It works, however it

isn't ideal since it's disconnected from Esri's authoritative data thus

updates require a manual process on our end. It's also a Feature Service

where we'd ideally like to use a Dynamic Map service for the sake of speed.

Plus, we'd obviously prefer not to spend credits on essentially duplicating

an ready-to-go layer.

Looking forward to trying it out in the next release though and seeing how

it goes.

-Todd

Re: AGSArcGISMapImageLayer and Identify

ToddAtkins — Sun, 12 Dec 2021 15:59:26 GMT

Mark, thanks for the info and that did the trick! I totally missed that in the docs.

One followup: the id result is only returning a handful of fields (example below) from the service when there are probably close 1,000 or more defined. Is there a way to specify additional fields to return?

{
 AREA = "581.277560472";
 ID = 05133;
 NAME = "Sevier County";
 OBJECTID = 178;
 "ST_ABBREV" = AR;
 "ST_NAME" = Arkansas;
 "Shape_Area" = "2195854296.001275";
 "Shape_Length" = "305710.4212080084";
}