RealityKit – Error: 'translation' is inaccessible due to 'internal' protection level

Question

I'm new to Swift, I'm programming an AR app with RealityKit for the app interface and a Wrapped SwiftUI struct inside one of those View Controllers, so I can create a custom AR interface. (I don't know if that's the proper way to do it, but as I told you, been learning by myself and managed to do it until now).

Anyway, the objective is to place AR objects according to a latitude and longitude given by the user (still haven't done that part, but I'm testing with manual values), a good approach to accomplish that will be to use ARGeoTrackingConfiguration() (from what I've read) but because my device (iPhone 7) doesn't have an A12 Bionic chip, I can't use it, so I am trying to implement it with ARWorldTrackingConfiguration(), but so far, I got stuck whit the issue of 'translation' is inaccessible due to 'internal' protection level when trying to get the location of the touch on the screen with self.raycast(...).first?.worldTransform.translation

extension ARView {

    @objc func handleTap(_ sender: UITapGestureRecognizer? = nil) {
    
        guard let touchInView = sender?.location(in: self) else {
            print("Failed on touch")
            return
        }
    
        let results = self.raycast(from: touchInView, 
                               allowing: .estimatedPlane, 
                              alignment: .horizontal)
        print(results)
    
        if let firstResult = results.first {
            let anchor = ARGeoAnchor(name: "pinus_pinaster.usdz", 
                           coordinate: firstResult.worldTransform.translation)
            self.session.add(anchor: anchor)
        } else {
            print("Object placement failed - coudn't find surface")
        }       
    }
}

Any explanations about how to solve this issue (an example would be nice)?

Also, any general advice for ARKit development, would it be possible to implement an app with these functionalities without ARGeoTrackingConfiguration() ?

Answer 1

1. Try using public access level, instead of internal:

    extension ARView { 
   
        @objc public func handleTap(_ sender: UIGestureRecognizer) { }
    }
   

2. It makes no sense to use ARGeoAnchors without running ARGeoTrackingConfiguration().

Answer 2

If you're using the ARKit geo tracking example from Apple, you might notice that transform is accessed via an extension of simd_float4x4 in Utilities.swift:

extension simd_float4x4 {
    var translation: SIMD3<Float> {
        get {
            return SIMD3<Float>(columns.3.x, columns.3.y, columns.3.z)
        }
        set (newValue) {
            columns.3.x = newValue.x
            columns.3.y = newValue.y
            columns.3.z = newValue.z
        }
    }
}

What this code does is extend the data type simd_float4x4, and create a transform property which is accessible from an instance of a simd_float4x4 (such as worldTransform.translation.)