Okay, I've figured out a few things here, in case someone has similar issues:
I was holding it wrong in that there was an issue with changes not being picked up by the binding. After I fixed that, the attachments: handler did get called again. Hooray.
The old AttachmentView did stick around though, due to the IDs of my attachments changing when they changed shape. I fixed this by making sure those IDs are stable, and calling content.add(...) again in the update: handler then updated those to the new look.
The remaining issues was to get rid of all attachment entities if they disappear from my Binding. I'm not particularly happy with it, but the solution I came up with, was to collect the IDs and then iterate through all entities to check if their IDs are still in my set:
let allEntities = Array(content.entities)
for entity in allEntities {
if let attachmentEntity = entity as? ViewAttachmentEntity, let id = attachmentEntity.attachment.id as? String, !goodIDs.contains(id) {
content.remove(attachmentEntity)
}
}
Would love to know if there's a better way to do this.
