This was running fine till GM Xcode (and iOS 11). Now I get these errors:

Apple Mach-O Linker (ld) Error Group
  "__T0So20AVCapturePhotoOutputC12AVFoundation01_abC16SwiftNativeTypesACWP", referenced from:
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"__T012AVFoundation37_AVCapturePhotoOutputSwiftNativeTypesPAAE012availableRawc11PixelFormatG0SaySo8NSNumberCGfg", referenced from:
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"  "__T0So22AVCapturePhotoSettingsC12AVFoundation01_abC16SwiftNativeTypesACWP", referenced from:
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ld: symbol(s) not found for architecture arm64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Some of the lines it’s pointing at are:

photoSettings = AVCapturePhotoSettings(rawPixelFormatType: OSType(self.photoOutput.availableRawPhotoPixelFormatTypes.first!))
photoSettings.previewPhotoFormat = [kCVPixelBufferPixelFormatTypeKey as String: photoSettings.availablePreviewPhotoPixelFormatTypes.first!.uint32Value,
                                                kCVPixelBufferWidthKey as String: 3024, kCVPixelBufferHeightKey as String: 3024]

Also:

let rawFormat = self.photoOutput.availableRawPhotoPixelFormatTypes.first!.uint32Value
photoSettings = AVCapturePhotoSettings(rawPixelFormatType: OSType(rawFormat),
                            processedFormat: [AVVideoCodecKey : AVVideoCodecJPEG,
                                              AVVideoCompressionPropertiesKey : [AVVideoQualityKey : 1.0]] as [String : Any])
            photoSettings.previewPhotoFormat = [kCVPixelBufferPixelFormatTypeKey as String: photoSettings.availablePreviewPhotoPixelFormatTypes.first!.uint32Value,
                                                kCVPixelBufferWidthKey as String: 3024,
                                                kCVPixelBufferHeightKey as String: 3024]