Swift - Camera with device rotation in Object Detection

Question

I was looking at this tutorial (https://developer.apple.com/documentation/vision/recognizing_objects_in_live_capture) and the problem is that when you rotate the device the view of the camera don't change frame size so you'll have a black space.

Any ideas to solve this problem?

In addition, I made my version of the app in SwiftUI (but the problem persists), so solution using SwiftUI are also appreciated!

Thanks in advance

Answer 1

I'm not sure how in SwiftUI, but here's how in UIKit:

Try setting the videoGravity:

cameraView.videoPreviewLayer.videoGravity = .resizeAspectFill

Then, this should take care of the orientation. This is based off of this answer.

override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
    super.viewWillTransition(to: size, with: coordinator)
    
    let cameraPreviewTransform = self.cameraView.transform
    
    coordinator.animate { (context) in
        
        let deltaTransform = coordinator.targetTransform
        let deltaAngle: CGFloat = atan2(deltaTransform.b, deltaTransform.a)
        
        var currentRotation = atan2(cameraPreviewTransform.b, cameraPreviewTransform.a)
        
        // Adding a small value to the rotation angle forces the animation to occur in a the desired direction, preventing an issue where the view would appear to rotate 2PI radians during a rotation from LandscapeRight -> LandscapeLeft.
        currentRotation += -1 * deltaAngle + 0.0001;
        self.cameraView.layer.setValue(currentRotation, forKeyPath: "transform.rotation.z")
        self.cameraView.layer.frame = self.view.bounds
    } completion: { (context) in
        let currentTransform : CGAffineTransform = self.cameraView.transform
        self.cameraView.transform = currentTransform
    }
}