Correctly set the right picture orientation when shooting photo

Question

On my iOS app written in Swift I need to take pictures and save them on gallery; as Apple documentation, all the pictures are taken in landscape also if the phone is in portrait; if we save the picture as-is it will be saved 90° rotated.

The question: How can I correctly manage the device orientation when saving picture?

Thank to some searches I used this solution:

    func photoOutput(_ output: AVCapturePhotoOutput, didFinishProcessingPhoto photo: AVCapturePhoto, error: Error?) {
        // ...error handling here

        guard let imageData = photo.fileDataRepresentation(with: self) else {
            NSLog("Fail to convert pixel buffer")
            return
        }
        
        // Save image to gallery here
    }

My class is AVCapturePhotoFileDataRepresentationCustomizer delegate, so:

    func replacementMetadata(for photo: AVCapturePhoto) -> [String : Any]? {
        var properties = photo.metadata

        // Image orientation
        properties[kCGImagePropertyOrientation as String] = CGImagePropertyOrientation.right
        
        let exifData = NSMutableDictionary(dictionary: properties[kCGImagePropertyExifDictionary as String] as! NSDictionary)
        let xDimension = exifData[kCGImagePropertyExifPixelYDimension as String]
        let yDimension = exifData[kCGImagePropertyExifPixelXDimension as String]
        
        if xDimension != nil && yDimension != nil {
            exifData[kCGImagePropertyExifPixelXDimension as String] = xDimension
            exifData[kCGImagePropertyExifPixelYDimension as String] = yDimension
            
            properties[kCGImagePropertyExifDictionary as String] = exifData
        }
        
        return properties
    }

Because the image is shot in portrait the orientation is .right and I read in my searches that also the X and Y dimensions in exif data should be swapped.

Unfortunately everything lead no result: Inspecting the saved image with an exif explorer image orientation is still a 0=unknown value and X and Y as originally set.

I'm sure the data is correctly set and written because:

1. Breakpoing on return properties underlined that the orientation tag set correctly; moreover if a tag is not correctly set or unknown the app crashes...

2. In the same replacementMetadata function I also set GPS data (I cut this for simplicity here!) and I wrote some test value (like heading = 101) and these data are correctly reported on the final image metadata.

So my question remains ... Thank you for pointing me in the right direction with code snippets or documents.

Answer 1

You may set your shot orientation to whatever you like by setting videoOrientation of your AVCapturePhotoOutput.

To match it with the current device orientation, you may use UIDevice.current.orientation manually converted to AVCaptureVideoOrientation.

let photoOutput = AVCapturePhotoOutput()

func takeShot() {

    // set whatever orientation you like
    let myShotOrientation = UIDevice.current.orientation.asCaptureVideoOrientation

    if let photoOutputConnection = self.photoOutput.connection(with: .video) {
        photoOutputConnection.videoOrientation = myShotOrientation
    }

    photoOutput.capturePhoto(...)
}

Conversion from UIDeviceOrientation to AVCaptureVideoOrientation:

extension UIDeviceOrientation {
    
    ///
    var asCaptureVideoOrientation: AVCaptureVideoOrientation {
        switch self {
        // YES, that's not a mistake
        case .landscapeLeft: return .landscapeRight
        case .landscapeRight: return .landscapeLeft
        case .portraitUpsideDown: return .portraitUpsideDown
        default: return .portrait
        }
    }
}