How to save a CapturedRoom using NSCoder - swift

Question

I'm trying to build an app that creates a floor plan of a room. I used ARWorldMap with ARPlaneAnchors for this but I recently discovered the Beta version of the RoomPlan API, which seems to lead to far better results.
However, I used te be able to just save an ARWorldMap using the NSCoding protocol, but this throws an error when I try to encode a CapturedRoom object:
-[__SwiftValue encodeWithCoder:]: unrecognized selector sent to instance 0x141c18110
My code for encoding the class containing the CapturedRoom:
import RoomPlan
class RoomPlanScan: NSObject, NSCoding {
var capturedRoom: CapturedRoom
var title: String
var notes: String
init(capturedRoom: CapturedRoom, title: String, notes: String) {
self.capturedRoom = capturedRoom
self.title = title
self.notes = notes
}
required convenience init?(coder: NSCoder) {
guard let capturedRoom = coder.decodeObject(forKey: "capturedRoom") as? CapturedRoom,
let title = coder.decodeObject(forKey: "title") as? String,
let notes = coder.decodeObject(forKey: "notes") as? String
else { return nil }
self.init(
capturedRoom: capturedRoom,
title: title,
notes: notes
)
}
func encode(with coder: NSCoder) {
coder.encode(capturedRoom, forKey: "capturedRoom")
coder.encode(title, forKey: "title")
coder.encode(notes, forKey: "notes")
}
}
To be clear, the following code does work:
import RoomPlan
class RoomPlanScan: NSObject, NSCoding {
var worldMap: ARWorldMap
var title: String
var notes: String
init(worldMap: ARWorldMap, title: String, notes: String) {
self.worldMap = worldMap
self.title = title
self.notes = notes
}
required convenience init?(coder: NSCoder) {
guard let capturedRoom = coder.decodeObject(forKey: "worldMap") as? ARWorldMap,
let title = coder.decodeObject(forKey: "title") as? String,
let notes = coder.decodeObject(forKey: "notes") as? String
else { return nil }
self.init(
worldMap: worldMap,
title: title,
notes: notes
)
}
func encode(with coder: NSCoder) {
coder.encode(worldMap, forKey: "worldMap")
coder.encode(title, forKey: "title")
coder.encode(notes, forKey: "notes")
}
}
I'm writing the object to a local file using NSKeyedArchiver so it would be nice if I could keep the same structure using NSCoder. How can I fix this and save a CapturedRoom?

Answer 1

The issue is about saving CaptureRoom. According to the doc, it's not NS(Secure)Coding compliant, but it conforms to Decodable, Encodable, and Sendable
So you can use an Encoder/Decoder, to do CaptureRoom <-> Data, you could use the bridge NSData/Data, since NSData is NS(Secure)Coding compliant.
So, it could be something like the following code. I'll use JSONEncoder/JSONDecoder as partial Encoder/Decoder because they are quite common.
Encoding:
let capturedRoomData = try! JSONEncoder().encode(capturedRoom) as NSData
coder.encode(capturedRoomData, forKey: "capturedRoom")
Decoding:
let captureRoomData = coder.decodeObject(forKey: "capturedRoom") as! Data
let captureRoom = try! JSONDecoder().decode(CaptureRoom.self, data: captureRoomData)
Side note:
I used force unwrap (use of !) to simplify the code logic, but of course, you can use do/try/catch, guard let, if let, etc.)