人脸识别变量（google-cloud-vision）

Question

我正在努力将人脸识别实现到iOS应用程序中。我收到许多标签，如'眼镜'或'微笑'，但没有看到一个实际的变量告诉我它是一个人脸（以及有多大程度的自信）。

我错过了什么变量，我们如何使用该功能？

Answer 1

我认为您可能没有使用正确的功能类型，因为您似乎正在获取标签而不是面部属性。

我建议您查看Detecting Faces和Face Detection Tutorial文档，您可以在其中找到详细信息和一些有用的示例，您可以将其用作参考，以了解有关使用Vision API的detecting faces过程的更多信息。

Answer 2

您可以按照几个步骤检测图像中的面部。

1. 创建您的URLRequest

   func createRequest() -> URLRequest? {
       // Create your request URL
       if let url =  URL(string: "YOUR_API_KEY") {
           var request = URLRequest(url: url)
           request.httpMethod = "POST"
           request.addValue("application/json", forHTTPHeaderField: "Content-Type")
           request.addValue(Bundle.main.bundleIdentifier ?? "", forHTTPHeaderField: "X-  Ios-Bundle-Identifier")
           let jsonRequest = [
               "requests": [
                   "features": [
                       [
                           "type": "FACE_DETECTION",
                           "maxResults": 10 //change as per your requirement
                       ]
                   ]
               ]
           ]
           let jsonData = try? JSONSerialization.data(withJSONObject: jsonRequest)
           request.httpBody = jsonData
           return request
       }
       return nil
   }

2. 在后台线程中运行请求

   let task: URLSessionDataTask = URLSession.shared.dataTask(with: request) { (data, response, error) in
       guard let data = data, error == nil else {
           print(error?.localizedDescription ?? "")
           return
       }
       print(data)// Analyze with this data
   }
   task.resume()

3. 分析数据（如果要更新任何UI组件，则在主线程上）

    DispatchQueue.main.async(execute: {
            do {
                guard let json =
                    try JSONSerialization.jsonObject(with: data, options: []) as? [String: Any] else { return }
                guard let responses = json["responses"] as? NSArray else { return }
                if responses.count > 0 {
                    guard let response = responses.firstObject as? [String: Any] else { return }
                    guard let faceAnnotations = response["faceAnnotations"] as? NSArray else {
                        print(false, "No face detected, please try another photo.")
                        return
                    }
                    if faceAnnotations.count > 0 {
                        print("Face successfully detected: \(faceAnnotations.count)")
                    }  else {
                        print("No face detected, please try another photo.")
                    }
                } else {
                    print("Error while face detection process, please try again.")
                }
            } catch {
                print("Error while face detection process, please try again.")
            }            
        })