Swift IOS Display AR QuickLook preview of downloaded usdz model - ios

Question

this is my first time trying to add an AR preview into an app (also my first time using the file system). I have been trying to implement a solution similar to that explained here https://developer.apple.com/forums/thread/126377 however one key difference is that my usdz model is not in my main bundle as it is generated and downloaded from an external source at run time. I was wondering if it is possible to display a file stored in the apps documents or cache directory and how it is done.
The file is downloaded and stored in the caches directory as follows:
class ModelFetcher: NSObject{
var modelUrl: URL?
func generateModel() {
guard let url = URL(string: "http://127.0.0.1:5000/model.usdz") else {return}
let urlSession = URLSession(configuration: .default, delegate: self, delegateQueue: OperationQueue())
var request = URLRequest(url: url)
request.httpMethod = "POST"
let downloadTask = urlSession.downloadTask(with: request)
downloadTask.resume()
}
}
extension ModelFetcher: URLSessionDownloadDelegate {
func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) {
print("File Downloaded Location- ", location)
guard let url = downloadTask.originalRequest?.url else {
return
}
let docsPath = FileManager.default.urls(for: .cachesDirectory, in: .userDomainMask)[0]
let destinationPath = docsPath.appendingPathComponent(url.lastPathComponent)
try? FileManager.default.removeItem(at: destinationPath)
do {
try FileManager.default.copyItem(at: location, to: destinationPath)
self.modelUrl = destinationPath
print("File moved to: \(modelUrl!.absoluteURL)")
} catch let error {
print("Copy Error: \(error.localizedDescription)")
}
}
}
I then try to display the model using ARQuicklookPreview as follows:
import SwiftUI
import QuickLook
import ARKit
struct ARQuickLookView: UIViewControllerRepresentable {
var allowScaling: Bool = true
func makeCoordinator() -> ARQuickLookView.Coordinator {
Coordinator(self)
}
func makeUIViewController(context: Context) -> QLPreviewController {
let controller = QLPreviewController()
controller.dataSource = context.coordinator
return controller
}
func updateUIViewController(_ controller: QLPreviewController,
context: Context) {
// nothing to do here
}
class Coordinator: NSObject, QLPreviewControllerDataSource {
let parent: ARQuickLookView
let destinationPath = FileManager.default.urls(for: .cachesDirectory, in: .userDomainMask)[0].appendingPathComponent("model.usdz")
private lazy var fileURL: URL = destinationPath
init(_ parent: ARQuickLookView) {
self.parent = parent
super.init()
}
func numberOfPreviewItems(in controller: QLPreviewController) -> Int {
return 1
}
func previewController(
_ controller: QLPreviewController,
previewItemAt index: Int
) -> QLPreviewItem {
let fileURL = FileManager.default.urls(for: .cachesDirectory, in: .userDomainMask)[0].appendingPathComponent("model.usdz")
print(fileURL)
let item = ARQuickLookPreviewItem(fileAt: fileURL)
print(item)
item.allowsContentScaling = parent.allowScaling
return item
}
}
}
struct ARQuickLookView_Previews: PreviewProvider {
static var previews: some View {
ARQuickLookView()
}
}
However, I receive the error "Unhandled item type 13: contentType is: (null) #PreviewItem" in the console and in the UI it reads unsupported file type, I have performed tests to make sure the file is in the location of the URL and I can even open it in preview on my mac so it's not like the file format or location is wrong.
Any help on displaying a model from a location other than the main bundle would be helpful, or perhaps a workaround to first move the file then display it.
Edit: After changing the preview controller function to
let fileURL = FileManager.default.urls(for: .cachesDirectory, in: .userDomainMask)[0].appendingPathComponent("model.usdz")
return fileUrl as QLPreviewItem
Now in the UI it just says "model universal scene description Package"
And in the console I still get an error however now it reads: Unhandled item type 13: contentType is: com.pixar.universal-scene-description-mobile #PreviewItem
Which doesn't make sense as that it one of the only types it supports
Thanks,
Louis