SwiftUI - How Can I Recognize Words And Get Positions In Vision
Introduction
In this article, we will explore how to use Apple's Vision framework to recognize words and get their positions in a SwiftUI application. We will build upon the code provided in the Medium article by Jakir, which demonstrates how to perform text recognition using Vision. However, we will focus on modifying the code to extract the bounding boxes of the recognized words.
Prerequisites
Before we begin, make sure you have the following:
- Xcode 13 or later
- iOS 15 or later
- SwiftUI 3 or later
- Apple Vision framework
Step 1: Setting up the Project
Create a new SwiftUI project in Xcode and add the Apple Vision framework to your project. You can do this by going to File > Add Packages..., searching for "Vision", and adding the framework.
Step 2: Importing the Vision Framework
In your SwiftUI view, import the Vision framework:
import SwiftUI
import Vision
Step 3: Creating a Text Recognition Model
Create a new class that will handle the text recognition using Vision:
class TextRecognizer {
let textRecognitionRequest = VNRecognizeTextRequest { request, error in
if let error = error {
print("Error: \(error)")
return
}
guard let results = request.results as? [VNRecognizedText] else {
print("No results")
return
}
for result in results {
print("Text: \(result.topCandidates(1).first?.string ?? "")")
}
}
func recognizeText(in image: UIImage) {
let handler = VNImageRequestHandler(ciImage: CIImage(image: image)!)
do {
try handler.perform([textRecognitionRequest])
} catch {
print("Error: \(error)")
}
}
}
This class creates a VNRecognizeTextRequest and sets up a handler to process the results.
Step 4: Modifying the Text Recognition Request
To get the bounding boxes of the recognized words, we need to modify the text recognition request to include the VNTextObservation type:
class TextRecognizer {
let textRecognitionRequest = VNRecognizeTextRequest { request, error in
if let error = error {
print("Error: \(error)")
return
}
guard let results = request.results as? [VNTextObservation] else {
print("No results")
return
}
for result in results {
print("Text: \(result.topCandidates(1).first?.string ?? "")")
print("Bounds: \(result.boundingBox)")
}
}
func recognizeText(in image: UIImage) {
let handler = VNImageRequestHandler(ciImage: CIImage(image: image)!)
do {
try handler.perform([textRecognitionRequest])
} catch {
print("Error: \(error)")
}
}
}
This modified request will return VNTextObservation objects, which contain the bounding boxes of the recognized words.
Step 5: Using the Text Recognizer in SwiftUI
Create a new SwiftUI view that uses the TextRecognizer class:
struct TextRecognitionView: View {
@State private var image: UIImage?
@State private var text: String = ""
@State private var bounds: CGRect = .zero
var body: some View {
VStack {
if let image = image {
Image(uiImage: image)
.resizable()
.scaledToFit()
}
Text(text)
.font(.largeTitle)
Text("Bounds: \(bounds)")
.font(.largeTitle)
}
}
.onAppear {
let recognizer = TextRecognizer()
recognizer.recognizeText(in: UIImage(named: "image")!) { text, bounds in
self.text = text
self.bounds = bounds
}
}
}
}
This view uses the TextRecognizer class to recognize the text in an image and display the recognized text and bounding box.
Conclusion
Q: What is the Apple Vision framework?
A: The Apple Vision framework is a powerful tool for computer vision tasks, including image recognition, object detection, and text recognition. It provides a set of APIs and tools for developers to build applications that can analyze and understand visual data.
Q: What is text recognition, and how does it work?
A: Text recognition, also known as Optical Character Recognition (OCR), is the process of converting images of text into editable text. The Apple Vision framework uses machine learning algorithms to analyze the pixels in an image and identify the shapes and patterns that correspond to letters and words.
Q: How do I use the Apple Vision framework in SwiftUI?
A: To use the Apple Vision framework in SwiftUI, you need to import the framework and create a VNRecognizeTextRequest object. You can then use the perform method to execute the request and get the recognized text and bounding boxes.
Q: What is the difference between VNRecognizedText and VNTextObservation?
A: VNRecognizedText is a class that represents a single recognized text string, while VNTextObservation is a class that represents a text observation, which includes the recognized text and its bounding box.
Q: How do I get the bounding box of a recognized text?
A: To get the bounding box of a recognized text, you need to use the VNTextObservation class and access its boundingBox property.
Q: Can I use the Apple Vision framework for other computer vision tasks?
A: Yes, the Apple Vision framework provides a wide range of APIs and tools for various computer vision tasks, including image recognition, object detection, and tracking.
Q: What are the system requirements for using the Apple Vision framework?
A: The Apple Vision framework requires iOS 15 or later and Xcode 13 or later.
Q: Can I use the Apple Vision framework in other Apple platforms?
A: Yes, the Apple Vision framework is available on other Apple platforms, including macOS, watchOS, and tvOS.
Q: How do I handle errors when using the Apple Vision framework?
A: You can handle errors when using the Apple Vision framework by checking the error parameter in the VNRecognizeTextRequest handler.
Q: Can I use the Apple Vision framework for real-time text recognition?
A: Yes, the Apple Vision framework provides APIs for real-time text recognition, which allows you to recognize text in real-time as the user types.
Q: How do I optimize the performance of the Apple Vision framework?
A: You can optimize the performance of the Apple Vision framework by using the VNImageRequestHandler class to handle the image processing and by using the VNRecognizeTextRequest class to handle the text recognition.
Q: Can I use the Apple Vision framework for other languages?
A: Yes, the Apple Vision framework supports multiple languages, including English, Spanish, French, German, Italian, Portuguese, Dutch, Russian, Chinese, Japanese, and Korean.
Q: How do I get started with the Apple Vision framework?
A: To get started with the Apple Vision framework, you need to import the framework and create a VNRecognizeTextRequest object. You can then use the perform method to execute the request and get the recognized text and bounding boxes.