{"id":2654,"date":"2020-06-28T10:00:00","date_gmt":"2020-06-28T08:00:00","guid":{"rendered":"http:\/\/www.albertopasca.it\/whiletrue\/?p=2654"},"modified":"2022-01-28T15:34:24","modified_gmt":"2022-01-28T14:34:24","slug":"swift-native-ocr-reader","status":"publish","type":"post","link":"https:\/\/www.albertopasca.it\/whiletrue\/swift-native-ocr-reader\/","title":{"rendered":"Swift – Native OCR reader"},"content":{"rendered":"\n

Starting from iOS 11, Apple introduces a new framework called Vision<\/strong>.<\/p>\n\n\n\n

The Vision framework performs face and face landmark detection, text detection, barcode recognition, image registration, and general feature tracking. Vision also allows the use of custom Core ML models for tasks like classification or object detection.<\/p>https:\/\/developer.apple.com\/documentation\/vision<\/a><\/cite><\/blockquote>\n\n\n\n

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Today we implement with few lines of code one of the simplest features of this beautiful framework, the OCR reader.<\/p>\n\n\n\n\n\n\n\n

OCR<\/strong> means: O<\/strong>ptical C<\/strong>haracter R<\/strong>ecognition. If you want to learn more, wikipedia helps you: https:\/\/en.wikipedia.org\/wiki\/Optical_character_recognition<\/a>.<\/p>\n\n\n\n

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L<\/strong>et’s start!<\/h2>\n\n\n\n

Create a new empty XCode project and a simple interface like this beautiful one:<\/p>\n\n\n\n

\"\"<\/figure><\/div>\n\n\n\n

Composed of an UIImageView<\/strong>, an UITextView<\/strong> and UIButton<\/strong>.<\/p>\n\n\n\n

Connect outlets and actions and prepare the code!<\/p>\n\n\n\n

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I<\/strong>mport Vision framework<\/h2>\n\n\n\n

First stuff, simplest is to add the new framework. So on top of your view controller, add:<\/p>\n\n\n\n

import UIKit\nimport Vision\nimport VisionKit\n<\/code><\/pre>\n\n\n\n
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S<\/strong>how the DocumentCameraViewController<\/h2>\n\n\n\n
Second thing, just to make a test, show the new VNDocumentCameraViewController<\/strong> that helps you to catch the document from any angle!<\/p>\n\n\n\n
Attach the code to a button action:<\/p>\n\n\n\n
@IBAction func didScanPressed(_ sender: Any) {\n    let scanVC = VNDocumentCameraViewController()\n    scanVC.delegate = self\n    present(scanVC, animated: true)\n}<\/code><\/pre>\n\n\n\n
Remember to add the delegates needed:<\/p>\n\n\n\n
extension ViewController: VNDocumentCameraViewControllerDelegate {\n\n    func documentCameraViewController(_ controller: VNDocumentCameraViewController,\n                                      didFinishWith scan: VNDocumentCameraScan)\n    {\n        guard scan.pageCount >= 1 else {\n            controller.dismiss(animated: true)\n            return\n        }\n\n        imgDocument.image = scan.imageOfPage(at: 0)\n        processImage(scan.imageOfPage(at: 0))\n        controller.dismiss(animated: true)\n    }\n    \n    func documentCameraViewController(_ controller: VNDocumentCameraViewController,\n                                      didFailWithError error: Error)\n    {\n        controller.dismiss(animated: true)\n    }\n    \n    func documentCameraViewControllerDidCancel(_ controller: VNDocumentCameraViewController) {\n        controller.dismiss(animated: true)\n    }\n\n}\n<\/code><\/pre>\n\n\n\n
The VNDocumentCameraViewController<\/strong> is your new photo view controller.<\/p>\n\n\n\n
You can automatically recognize the documents<\/strong>, can adjust colors<\/strong>, crop<\/strong>, resize<\/strong>, align<\/strong> and much more… and the picture is taken automatically<\/em>!<\/p>\n\n\n\n
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\"\"<\/figure>\n\n\n\n
\"\"<\/figure>\n\n\n\n
\"\"<\/figure>\n<\/figure>\n\n\n\n
Cool<\/strong>… but now we want to read the text of our documents!<\/p>\n\n\n\n
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I<\/strong>mplement the Text Request<\/h2>\n\n\n\n
Start creating the class:<\/p>\n\n\n\n
private var ocrRequest = VNRecognizeTextRequest(completionHandler: nil)<\/code><\/pre>\n\n\n\n
Now we need to configure our request.<\/p>\n\n\n\n
The VNRecognizeTextRequest<\/strong> have different options that can be used:<\/p>\n\n\n\n