SwiftUI Data Scanner Test

This projects demonstrates a problem in SwiftUI when embedding DataScannerViewController in UIViewControllerRepresentable. It has been created based on StackOverflow questions and its associated code.

The setup

• DataScannerViewController is wrapped in a UIViewControllerRepresentable conforming DataScannerView (in file DataScannerView.swift). It will detect barcode/text elements (based on some input parameters).

• ViewInsideScanView is embedding the DataScannerView if access to the camera has been granted, otherwise a text message is shown.
  The headerView (presented as a sheet) allows changing the type of scan.

• ScanView is integrating ViewInsideScanView in its layout.

• ContentView is combining a dummy "Home" view and the ScanView in a TabView.

The problem

The DataScannerViewController automatically stopps scanning and updating the camera preview, when the view disappears by switching the currently selected tab. When switching the tab back to the scanner view, the scanning does not restart, even though method startScanning() of DataScannerViewController is called.

The workaround

Recreating the DataScannerView instance is currently the only way to make it work again.
This is done by incrementing the appearCount of the current ScannerDataViewModel instance. This causes the dataScannerViewId to change, making SwiftUI think, that the DataScannerView has to be re-instantiated.