Confirming signature images contain signature strokes

[murjax]

I am using the epSignature delegate in the following:

let signatureVC = EPSignatureViewController(signatureDelegate: self)

if let signature = signatureView.getSignatureAsImage() {
    self.epSignature(signatureVC, didSign: signature, boundingRect: signatureView.getSignatureBoundsInCanvas())
}

I am checking for the existence of a signature before using it in the delegate. This works most of the time, and if my users do not attempt to sign then I can prevent the signature from being saved.

However I've seen blank signature images being saved lately. The user can simply tap on the signature view to generate the image, without ever drawing anything in the box. Is there a way to check the resulting image for strokes so I can prevent blank signature images from being saved?