Deprecate MLKit for iOS

[navaronbracke]

mobile_scanner currently uses MLKit on both iOS and Android.

However, for iOS there is a first-party library, namely the Vision API from Apple. We already use this implementation for MacOS.

We should switch iOS over to use that implementation, which brings a bunch of improvements. The following checklist lists the points that we should tackle when doing this migration:

• [x] lower the iOS deployment target back to Flutter's default of 12.0, as Vision is supported on minimum iOS 11
• [x] add back build support for arm64 iOS Simulators, which are unsupported on MLKit https://github.com/juliansteenbakker/mobile_scanner/pull/1228
• [x] merge both the iOS and MacOS implementation sources, https://github.com/juliansteenbakker/mobile_scanner/issues/782
• [ ] add support for the scan window, using https://developer.apple.com/documentation/vision/vnimagebasedrequest/regionofinterest
• [ ] backfill the barcode capture data, which previously was automatically provided by MLKit
• [x] remove the "unsupported" note - for iOS arm64 Simulators - on the iOS section of the readme https://github.com/juliansteenbakker/mobile_scanner/pull/1228
• [ ] fix flickering bug in the scan window overlay widget
  • Does the equality of the corners affect this? Maybe we need to use a threshold to compare the corners?
• [ ] fix barcode painter not repainting with no square when the barcode is no longer within the camera view

[juliansteenbakker]

I have created a first draft/beta of a shared ios & macos implementation of the Vision API. Please see ios-vision for the current code. It is working right now, but still needs some work on some of the features like zoom control. I will update this in the comming days.

[P0labrD]

Hello @juliansteenbakker My project would very much benefit from this change, I thank you for it 🙏 If you need any help to fasten the new release, I'd be happy to help 🙂

[juliansteenbakker]

I have uploaded a new version, v7.0.0-beta.2, with some fixes. Feel free to try it out!

[RutgerVleuten]

Just tested an integration of v7.0.0-beta.3, no issues found so-far ... looking forward to the public release!