Xcode 11.2.1 through an error (Cannot find protocol declaration for) on app-Swift.h

Question

I recently migrating Xcode 10.3 - 11.2.1, the project combination of Objective-C and Swift, I fixed most of the issue and finally I stuck in app-Swift.h file. It shows error "Cannot find protocol declaration for". Its working good in Xcode 10.2 not in Xcode 11.2.1

Kindly provide me an suggestion to fix this issue.

Swift Code Below

extension FaceScanHelper: AcuantHGLiveFaceCaptureDelegate {
    
    func liveFaceDetailsCaptured(liveFaceDetails: LiveFaceDetails?) {
        
        if(liveFaceDetails?.faceRect != nil && liveFaceDetails?.image != nil){
            
            faceImage = liveFaceDetails?.image
            
            let translatedFaceRect = self.calculateFaceRect(faceBounds: (liveFaceDetails?.faceRect?.toCGRect())!, clearAperture:(liveFaceDetails?.cleanAperture?.toCGRect())!)
            
            
            var width = (translatedFaceRect.width)
            width = 1.1*width
            
            var height = (translatedFaceRect.height)
            height = 1.3*height
            
            let x = (translatedFaceRect.origin.x) + ((translatedFaceRect.width)-width)
            let y = (translatedFaceRect.origin.y) + ((translatedFaceRect.height)-height)
            let faceRect =  CGRect.init(x: x, y: y, width: width, height:height)
            self.faceOval?.removeFromSuperlayer()
            faceOval = CAShapeLayer()
            faceOval?.path = UIBezierPath.init(ovalIn: faceRect).cgPath
            faceOval?.fillColor = UIColor.clear.cgColor
            faceOval?.strokeColor = UIColor.init(rgb: APP_THEME_COLOR).cgColor //UIColor.red.cgColor
            faceOval?.lineWidth = 5.0
            
            self.videoPreviewLayer.addSublayer((faceOval)!)
            if(liveFaceDetails?.isLiveFace)!{
                
                if let face = liveFaceDetails?.image{
                    if(!isReported){
                        isReported = true
                        self.delegate?.liveFaceCaptured!(face, error: nil)
                    }
                }
            }
        }else if(liveFaceDetails == nil || liveFaceDetails?.faceRect == nil){
            self.faceOval?.removeFromSuperlayer()
        }
    }
}

See the Swift file method declaration on below the screenshot

See the errors list its below screenshot all in same app-Swift.h