How to use a variable in a bind operation in Kotlin?

This seems like a very simple question but I can't seem to figure it out.

I have a bind operation using Kotlin ... for instance,

binding.crimePhoto1.setImageBitmap(scaledBitmap)

I want the "1" to actually be variable that references a changing counter. I can't seem to get the syntax right in Kotlin. I have set the variable within the same class where the binding is happening.

For instance:

var counter: Int = 1

...
binding.crimePhoto$counter.setImageBitmap(scaledBitmap) <---does not work

...
binding.crimePhoto{$counter}.setImageBitmap(scaledBitmap) <---does not work

...
binding.crimePhoto{counter}.setImageBitmap(scaledBitmap) <---look like it'll work but I get an error (Unresolved reference: crimePhoto)

I've tried the above permutations. I've tried setting it as a class variable and a variable within the function itself.

You can't do that kind of thing. binding.crimePhoto1 is just a variable on an object called binding, and outside of reflection shenanigans you can't refer to variables in Kotlin like that - you have to use their explicit name.

The typical way to do this kind of thing would be to create a collection of the items you're working with, and then refer to members of that collection with your changing value. Something like this:

val images = listOf(
    binding.crimePhoto1, binding.crimePhoto2
)
// or for shorthand, so you refer to binding once
val images = binding.run { listOf(crimePhoto1, crimePhoto2) }

// access the images
images
0
+
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.setImageBitmap(scaledBitmap)

There are other ways to build that collection instead of listing them explicitly - you could use theContainingLayout.children.filterIsInstance<ImageView> to pull out all the ImageViews at the top level of a layout (you'll need a recursive function if they're nested inside other layouts).

Or you could skip view binding, and generate a list of view IDs (similar to what you're trying to do), look them up with findViewById (creating a new list of ImageViews), and then use those:

val images = List(imageCount) { "crimePhoto{it + 1}" }
    .map { name -> resources.getIdentifier(name, packageName) }
    .mapNotNull { id -> findViewById<ImageView>(id) }

(I'm doing this by memory so I'm not sure if you need to explicitly cast to List<ImageView> in this situation - you could use filterIsInstance if you need to, and let that handle the nulls too)

The other nice thing about having a collection like this is you have a clearly defined set of elements - so you can iterate over them to set click listeners, use the collection size to set the bounds of counter, etc