Not detecting QR Code from a static image - ios

Question

I want to detect qrcode from still image
Here is the code
let ciimage = <Load image from asset and covert to CIImage>
let detector = CIDetector(ofType: CIDetectorTypeQRCode, context:nil, options:nil)
let features = detector.featuresInImage(ciimage)
print(features.count)
The image is correct CIImage instance which has QRCode but I always get no features, Have any one had the same issue?
Thank you very much.

Answer 1

I think I found answer
That code only works in Playground or real iPhone, it never works on simulator
I generated QRCode image using CIQRCodeGenerator CoreImage filter.
I hope someone can check my answer here and give me advice.
Below is source code what I used
enum QRCodeUtilError:ErrorType{
case GenerationFailed
}
extension UIImage {
/**
This function trys to return CIImage even the image is CGImageRef based.
- Returns: CIImage equal to current image
*/
func ciImage() -> CoreImage.CIImage?{
// if CIImage is not nil then return it
if self.CIImage != nil {
return self.CIImage
}
guard let cgImage = self.CGImage else {
return nil
}
return CoreImage.CIImage(CGImage: cgImage)
}
}
/**
QRCode utility class
*/
class QRCodeUtil{
/**
Generates 'H' mode qrcode image
- Parameter qrCode: QRCode String
- Returns: Optional UIImage instance of QRCode
*/
class func imageForQrCode(qrCode:String) throws -> UIImage{
guard let filter = CIFilter(name: "CIQRCodeGenerator") else {
throw QRCodeUtilError.GenerationFailed
}
guard let data = qrCode.dataUsingEncoding(NSISOLatin1StringEncoding) else {
throw QRCodeUtilError.GenerationFailed
}
filter.setValue(data, forKey: "inputMessage")
filter.setValue("H", forKey: "inputCorrectionLevel")
guard let outputImage = filter.outputImage else {
throw QRCodeUtilError.GenerationFailed
}
/*
Convert the image to CGImage based because
it crashes when saving image using
UIImagePNGRepresentation or UIImageJPEGRepresentation
if image is CIImage based.
*/
let context = CIContext(options: nil)
let cgImage = context.createCGImage(outputImage, fromRect: outputImage.extent)
return UIImage(CGImage: cgImage)
}
/**
Detects QRCode from string
- Parameter qrImage: UIImage which has QRCode
- Returns: QRCode detected
*/
class func qrCodeFromImage(qrImage:UIImage) -> String {
let detector = CIDetector(ofType: CIDetectorTypeQRCode, context: nil, options: [CIDetectorAccuracy:CIDetectorAccuracyHigh])
guard let ciImage = qrImage.ciImage() else {
return ""
}
guard let feature = detector.featuresInImage(ciImage).last as? CIQRCodeFeature else {
return ""
}
return feature.messageString
}
}