SwiftでGoogle Vision APIを使用してOCRした文字情報をテキストビューに表示する方法

画像の文字情報をOCRするiOSアプリを作成しています。

下記GitHubのページとQiitaのページを参照しましたが、OCRした文字情報がlabelResultsに表示されず、
Xcodeのコンソールに表示されています。
OCRをすると、「labelResults」テキストビューに、下記コードの「request.httpBody = data」以下が表示されます。
どのようにすればよいかご教授いただけないでしょうか。

GitHub:https://github.com/GoogleCloudPlatform/cloud-vision/tree/master/ios
Qiita:https://qiita.com/ahpjop/items/a36817bc5d8e25e634e3

Swift
1
2import UIKit
3import SwiftyJSON
4
5
6class ViewController: UIViewController, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
7    let imagePicker = UIImagePickerController()
8    let session = URLSession.shared
9    
10    @IBOutlet weak var imageView: UIImageView!
11    @IBOutlet weak var spinner: UIActivityIndicatorView!
12    @IBOutlet weak var labelResults: UITextView!
13    @IBOutlet weak var faceResults: UITextView!
14    
15    var googleAPIKey = "YOUR_API_KEY"
16    var googleURL: URL {
17        return URL(string: "https://vision.googleapis.com/v1/images:annotate?key=(googleAPIKey)")!
18    }
19    
20    @IBAction func loadImageButtonTapped(_ sender: UIButton) {
21        imagePicker.allowsEditing = false
22        imagePicker.sourceType = .photoLibrary
23        
24        present(imagePicker, animated: true, completion: nil)
25    }
26    
27    override func viewDidLoad() {
28        super.viewDidLoad()
29        // Do any additional setup after loading the view, typically from a nib.
30        imagePicker.delegate = self
31        labelResults.isHidden = true
32        faceResults.isHidden = true
33        spinner.hidesWhenStopped = true
34    }
35    
36    override func didReceiveMemoryWarning() {
37        super.didReceiveMemoryWarning()
38        // Dispose of any resources that can be recreated.
39    }
40}
41
42
43/// Image processing
44extension ViewController {
45    
46    func analyzeResults(_ dataToParse: Data) {
47        
48        // Update UI on the main thread
49        DispatchQueue.main.async(execute: {
50            
51            
52            // Use SwiftyJSON to parse results
53            let json = JSON(data: dataToParse)
54            let errorObj: JSON = json["error"]
55            
56            self.spinner.stopAnimating()
57            self.imageView.isHidden = true
58            self.labelResults.isHidden = false
59            self.faceResults.isHidden = false
60            self.faceResults.text = ""
61            
62            // Check for errors
63            if (errorObj.dictionaryValue != [:]) {
64                self.labelResults.text = "Error code (errorObj["code"]): (errorObj["message"])"
65            } else {
66                // Parse the response
67                print(json)
68                let responses: JSON = json["responses"][0]
69                
70                  
71                // Get label annotations
72                let labelAnnotations: JSON = responses["textAnnotations"]
73                let numLabels: Int = labelAnnotations.count
74                var labels: Array<String> = []
75                if numLabels > 0 {
76                    
77                    var labelResultsText:String = "Labels found: "
78                    for index in 0..<1 {
79                        let label = labelAnnotations[index]["description"].stringValue
80                        labels.append(label)
81                    }
82                    for label in labels {
83                        // if it's not the last item add a comma
84                        if labels[labels.count - 1] != label {
85                            labelResultsText += "(label), "
86                        } else {
87                            labelResultsText += "(label)"
88                        }
89                    }
90                    self.labelResults.text = labelResultsText
91                }
92            }
93        })
94        
95    }
96    
97    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {
98        if let pickedImage = info[UIImagePickerControllerOriginalImage] as? UIImage {
99            imageView.contentMode = .scaleAspectFit
100            imageView.isHidden = true // You could optionally display the image here by setting imageView.image = pickedImage
101            spinner.startAnimating()
102            faceResults.isHidden = true
103            labelResults.isHidden = true
104            
105            // Base64 encode the image and create the request
106            let binaryImageData = base64EncodeImage(pickedImage)
107            createRequest(with: binaryImageData)
108        }
109        
110        dismiss(animated: true, completion: nil)
111    }
112    
113    func imagePickerControllerDidCancel(_ picker: UIImagePickerController) {
114        dismiss(animated: true, completion: nil)
115    }
116    
117    func resizeImage(_ imageSize: CGSize, image: UIImage) -> Data {
118        UIGraphicsBeginImageContext(imageSize)
119        image.draw(in: CGRect(x: 0, y: 0, width: imageSize.width, height: imageSize.height))
120        let newImage = UIGraphicsGetImageFromCurrentImageContext()
121        let resizedImage = UIImagePNGRepresentation(newImage!)
122        UIGraphicsEndImageContext()
123        return resizedImage!
124    }
125}
126
127
128/// Networking
129extension ViewController {
130    func base64EncodeImage(_ image: UIImage) -> String {
131        var imagedata = UIImagePNGRepresentation(image)
132        
133        // Resize the image if it exceeds the 2MB API limit
134        if (imagedata?.count > 2097152) {
135            let oldSize: CGSize = image.size
136            let newSize: CGSize = CGSize(width: 800, height: oldSize.height / oldSize.width * 800)
137            imagedata = resizeImage(newSize, image: image)
138        }
139        
140        return imagedata!.base64EncodedString(options: .endLineWithCarriageReturn)
141    }
142    
143    func createRequest(with imageBase64: String) {
144        // Create our request URL
145        
146        var request = URLRequest(url: googleURL)
147        request.httpMethod = "POST"
148        request.addValue("application/json", forHTTPHeaderField: "Content-Type")
149        request.addValue(Bundle.main.bundleIdentifier ?? "", forHTTPHeaderField: "X-Ios-Bundle-Identifier")
150        
151        // Build our API request
152        let jsonRequest = [
153            "requests": [
154                "image": [
155                    "content": imageBase64
156                ],
157                "features": [
158                    [
159                        "type": "TEXT_DETECTION",
160                        "maxResults": 1
161                    ],
162                ]
163            ]
164        ]
165        let jsonObject = JSON(jsonDictionary: jsonRequest)
166        
167        // Serialize the JSON
168        guard let data = try? jsonObject.rawData() else {
169            return
170        }
171        
172        request.httpBody = data
173        
174        // Run the request on a background thread
175        DispatchQueue.global().async { self.runRequestOnBackgroundThread(request) }
176    }
177    
178    func runRequestOnBackgroundThread(_ request: URLRequest) {
179        // run the request
180        
181        let task: URLSessionDataTask = session.dataTask(with: request) { (data, response, error) in
182            guard let data = data, error == nil else {
183                print(error?.localizedDescription ?? "")
184                return
185            }
186            
187            self.analyzeResults(data)
188        }
189        
190        task.resume()
191    }
192}
193
194
195// FIXME: comparison operators with optionals were removed from the Swift Standard Libary.
196// Consider refactoring the code to use the non-optional operators.
197fileprivate func < <T : Comparable>(lhs: T?, rhs: T?) -> Bool {
198    switch (lhs, rhs) {
199    case let (l?, r?):
200        return l < r
201    case (nil, _?):
202        return true
203    default:
204        return false
205    }
206}
207
208// FIXME: comparison operators with optionals were removed from the Swift Standard Libary.
209// Consider refactoring the code to use the non-optional operators.
210fileprivate func > <T : Comparable>(lhs: T?, rhs: T?) -> Bool {
211    switch (lhs, rhs) {
212    case let (l?, r?):
213        return l > r
214    default:
215        return rhs < lhs
216    }
217}