Counting number of layers selected in ArcMap TOC using ArcObjects?

Question

Has anyone ever tried to get the number of layers that are selected in ArcMap? If I have a map document that has six layers and three of them are selected in the TOC, how does one count them using ArcObjects? I have looked for a while at IContentsView.SelectedItem. Documentation says it can be an enumerator, but I am having a hard time finding out actually what it's type is. In C#, if I do

string myType = IContentsView.SelectedItem.GetType().ToString();

myType is "System._ComObject". Not very descriptive... Trying

if(IContentsView.SelectedItem is IEnumLayer)

and similar checks has been unintuitive... I wasn't sure if multiple layers were selected that they would be stored in there but that was my first guess.

• Michael Stimson: There's an example here edndoc.esri.com/arcobjects/9.1/ComponentHelp/esriArcMapUI/… it should be IEnumObject edndoc.esri.com/arcobjects/9.2/ComponentHelp/esriGeoDatabase/…
• dlbran: Thanks, Michael. I think I saw something similar to this but I will give it another look when I have my code in front of me. I didn't remember seeing an IEnumObjects. Hopefully it is still there at 10.0.
• Michael Stimson: help.arcgis.com/en/sdk/10.0/arcobjects_net/componenthelp/… AND resources.arcgis.com/en/help/arcobjects-net/componenthelp/…

Answer 1

IContentsViewSelection should work for you.

http://resources.arcgis.com/en/help/arcobjects-net/componenthelp/index.html#//000v00000064000000

This is VB, but you should get the idea...

Dim pCVSel As IContentsViewSelection = My.ArcMap.Document.CurrentContentsView

Then: pCVSel.SelectedItems.Count will give you the count of selected items in the TOC.

• dlbran: Thanks, @Dan. This is probably cleaner than what I ended up doing. I looked at link and finally realized that SelectedItem is an ISet when it contains more than one object. I did the QI on that rather than on IContentsView. I will give you the answer though since you are correct. Thanks for your input!