IOS: Ambiguous Use of init(CGImage)

I am trying to convert a CGImage into a CIImage; however, it is not working.

This line of code:

let personciImage = CIImage(CGImage: imageView.image!.CGImage!)

throws the following error

Ambiguous use of 'init(CGImage)'

I'm really confused as to what this error means.

I need to do this conversion because CIDetector.featuresInImage() from the built in CoreImage framework requires a CIImage