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:

• lower the iOS deployment target back to Flutter's default of 12.0, as Vision is supported on minimum iOS 11
• add back build support for arm64 iOS Simulators, which are unsupported on MLKit feat: Vision API fixes #1228
• merge both the iOS and MacOS implementation sources, Use sharedDarwinSource to share MacOS and iOS implementation details #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
• remove the "unsupported" note - for iOS arm64 Simulators - on the iOS section of the readme feat: Vision API fixes #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
• investigate if we can fix analyzeImage not throw error when picking non-Qr image on iOS #1244
• Permission error not reset in start/stop method #1247

Nice to have also:

• How to disable/decrease noisy logs #1255
• placeholderBuilder and errorBuilder callbacks for MobileScanner have an extra argument which serves no purpose. #1256

[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!

[dincerkizildere]

Hello, is there any specific date set for the general release of version 7.0.0?

[lpl-code-github]

刚刚测试了 v7.0.0-beta.3 的集成，到目前为止没有发现任何问题...期待公开发布！

When using analyzeImage to analyze a QR code of an image, it will remain in 'await' and will not proceed further. #1244

[topdeveloper1219]

Oh....
where are you from @navaronbracke? Can you cooperate with us as soon as possible?

[navaronbracke]

@topdeveloper1219 Anyone is free to use the v7 beta. As for the issue with analyze image, I'd have to look into it. But if you do find why it isn't completing after the await, feel free to submit a pull request