func convertUIImageToCGImage(uiimage:UIImage)->CGImage{

        varcgimage = uiimage.cgImage

        ifcgimage ==nil{

            letciimage = uiimage.ciImage

            cgimage =self.convertCIImageToCGImage(ciimage:ciimage!)

        }

        return cgimage!

    }

UIimage转CGImage 

    func convertCIImageToCGImage(ciimage:CIImage)->CGImage{

        letciContext =CIContext.init()

        letcgimage:CGImage= ciContext.createCGImage(ciimage,from: ciimage.extent)!

        return cgimage

    }

CIImage转CGImage

        letimage =self.photoImageView.image!

        letnewimage =self.convertUIImageToCGImage(uiimage: image)

        letflippedImage =UIImage(cgImage: newimage,scale: image.scale,orientation:UIImage.Orientation.upMirrored)

这样就好了，不能直接采用UIImage.cgimage获取需要转化一遍才行