What is OCR?

Optical character recognition or optical character reader (OCR) is the electronic or mechanical conversion of images of typed, handwritten, or printed text into machine-encoded text, whether from a scanned document, a photo of a document, a scene-photo (for example the text on signs and billboards in a landscape photo) or from subtitle text superimposed on an image (for example: from a television broadcast).

The Vision framework allows the users to apply computer vision algorithms to perform a variety of tasks on input images and video.

What to expect?

Output: About Developed this app to easily extract code snippets from youtube tutorials which do not have a git link. Watching and typing becomes a tedious task at times. Anyways the repo name suggests it all. Live proj. Some commits might produce bugs.

Code block

Import Vision framework.

import vision

Add access to camera/photos so the user can click/select images for character recognition. Make sure to add the necessary permissions in info.plist

@IBAction func didTapCamera(){
       presentPhotoActionSheet()
}

extension ViewController: UIImagePickerControllerDelegate, UINavigationControllerDelegate{
   
   func presentPhotoActionSheet() {
       let actionSheet = UIAlertController(title: NSLocalizedString("Profile Picture", comment: "") ,
                                           message: NSLocalizedString("How would you like to select a picture?", comment: ""),
                                           preferredStyle: .actionSheet)
       actionSheet.addAction(UIAlertAction(title: NSLocalizedString("Cancel", comment: ""),
                                           style: .cancel,
                                           handler: nil))
       actionSheet.addAction(UIAlertAction(title: NSLocalizedString("Take Photo", comment: ""),
                                           style: .default,
                                           handler: { [weak self] _ in
                                               
                                               self?.presentCamera()
                                               
                                           }))
       actionSheet.addAction(UIAlertAction(title: NSLocalizedString("Chose Photo", comment: ""),
                                           style: .default,
                                           handler: { [weak self] _ in
                                               
                                               self?.presentPhotoPicker()
                                               
                                           }))       
       present(actionSheet, animated: true)
   }
   
   func presentCamera() {
       let vc = UIImagePickerController()
       vc.sourceType = .camera
       vc.delegate = self
       vc.allowsEditing = true
       
       present(vc, animated: true)
   }
   
   func presentPhotoPicker() {
       let vc = UIImagePickerController()
       vc.sourceType = .photoLibrary
       vc.delegate = self
       vc.allowsEditing = true
       present(vc, animated: true)
   }
   
   func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
       picker.dismiss(animated: true, completion: nil)
       guard let selectedImage = info[UIImagePickerController.InfoKey.editedImage] as? UIImage else {
           return
       }
       act.isHidden = false
       act.startAnimating()
       self.image.image = selectedImage
       recognizeText(image: selectedImage)
   }
   
   func imagePickerControllerDidCancel(_ picker: UIImagePickerController) {
       picker.dismiss(animated: true, completion: nil)
   }
}

Add function to recognize text from selected image.

    private func recognizeText(image: UIImage?){
        var textString = ""
        request = VNRecognizeTextRequest(completionHandler: {(request, error) in
            guard let observations = request.results as? [VNRecognizedTextObservation] else {
                return
            }
            
            for observation in observations {
                guard let topCandidate = observation.topCandidates(1).first else {
                    print("duh")
                    continue
                }
                textString += "\n\(topCandidate.string)"
                DispatchQueue.main.async {
                    self.act.isHidden = true
                    self.act.stopAnimating()
                    self.label.text = textString
                }
            }
            
        })
        request.recognitionLevel = .accurate
        request.usesLanguageCorrection = true
        
        let requests = [request]
        
        DispatchQueue.global(qos: .userInitiated).async {
            guard let img = image?.cgImage else {
                print("Nay")
                return
            }
            let handle = VNImageRequestHandler(cgImage: img, options: [:])
            try?handle.perform(requests)
        }
        
    }

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