UIImagePNGRepresentation always nil for generated QR image

Question

I am trying to save a QR code image that was generated in my app, and when doing so I am unable to get the underlying data so that I can save it.

The QR code is generated via CIFilters from a string, nothing special, like so:

 if let filter = CIFilter(name: "CIQRCodeGenerator") {

        //set the data to the contact data
        filter.setValue(contactData, forKey: "inputMessage")
        filter.setValue("L", forKey: "inputCorrectionLevel")

        if let qrImage = filter.outputImage {
            self.qrCode = UIImage(ciImage: codeImage)
        }
    }
}

And, I'm trying to get the image data to save it to the application documents by doing so:

let data = UIImagePNGRepresentation(self.qrCode)

But, it always returns nil.

I understand the documentation saying that it can return nil if no underlying data is found,

but I am confused at how I can store this image that is generated if there is no underlying data?

where are you calling the UIImagePNGRepresentation function? — Christian Abella, Jun 25 '18 at 23:50
Take a look at this thtead: https://stackoverflow.com/questions/28386344/cifilter-output-image-nil?rq=1 — user3581248, Jun 25 '18 at 23:51
@ChristianAbella I am calling it inside of a class that creates the image — Drew Wilken, Jun 26 '18 at 00:04
@ChristianAbella What specifically? The class is just a normal swift class that is initialized by passing as string, the QR image is generated just by running the code above, and outputted just from a function call, what else would you like to see ? — Drew Wilken, Jun 26 '18 at 00:15
because this is an async call filter.outputImage, and it is likely that when you call it to save it has not yet finish processing. — Christian Abella, Jun 26 '18 at 00:19

UIImagePNGRepresentation always nil for generated QR image

0 Answers0