open class CIDetector : NSObject {
 // 初始化方法
 public init?(ofType type: String, context: CIContext?, options: [String : Any]? = nil)
 // 獲取識別特征
 open func features(in image: CIImage) -> [CIFeature]
 open func features(in image: CIImage, options: [String : Any]? = nil) -> [CIFeature]
}
// 識別類型
public let CIDetectorTypeFace: String // 面部識別
public let CIDetectorTypeRectangle: String // 矩形識別
public let CIDetectorTypeQRCode: String // 條碼識別
public let CIDetectorTypeText: String // 文本識別
// 下面定義的就是options中可以傳的參數
public let CIDetectorAccuracy: String // 識別精度
public let CIDetectorAccuracyLow: String // 低精度，識別速度快
public let CIDetectorAccuracyHigh: String // 高精度，識別速度慢
public let CIDetectorTracking: String // 是否開啟面部追蹤
public let CIDetectorMinFeatureSize: String // 指定最小尺寸的檢測器，小于這個尺寸的特征將不識別，CIDetectorTypeFace(0.01 ~ 0.50)，CIDetectorTypeText(0.00 ~ 1.00)，CIDetectorTypeRectangle(0.00 ~ 1.00)
public let CIDetectorMaxFeatureCount: String // 設置返回矩形特征的最多個數 1 ~ 256 默認值為1
public let CIDetectorNumberOfAngles: String // 設置角度的個數 1, 3, 5, 7, 9, 11
public let CIDetectorImageOrientation: String // 識別方向
public let CIDetectorEyeBlink: String // 眨眼特征
public let CIDetectorSmile: String // 笑臉特征
public let CIDetectorFocalLength: String // 每幀焦距
public let CIDetectorAspectRatio: String // 矩形寬高比
public let CIDetectorReturnSubFeatures: String // 文本檢測器是否應該檢測子特征，默認值是否

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
 // 1.取到圖片
 let image = info[UIImagePickerController.InfoKey.originalImage] as? UIImage
 // 2.生成CIImage
 let ciimage = CIImage(cgImage: image!.cgImage!)
 // 3.識別精度
 let options = [CIDetectorAccuracy: CIDetectorAccuracyHigh]

 /**
 4.創建識別器，3個參數

 ofType：識別類型
 CIDetectorTypeFace 面部識別
 CIDetectorTypeText 文本識別
 CIDetectorTypeQRCode 條碼識別
 CIDetectorTypeRectangle 矩形識別

 context：上下文，默認傳nil

 options：識別精度
 CIDetectorAccuracyLow 低精度，識別速度快
 CIDetectorAccuracyHigh 高精度，識別速度慢
 */
 let detector = CIDetector(ofType: CIDetectorTypeQRCode, context: nil, options: options)

 /**
 5.獲取識別結果，2個參數

 in：需要識別的圖片

 options：需要識別的特征
 CIDetectorMinFeatureSize: 指定最小尺寸的檢測器，小于這個尺寸的特征將不識別，CIDetectorTypeFace(0.01 ~ 0.50)，CIDetectorTypeText(0.00 ~ 1.00)，CIDetectorTypeRectangle(0.00 ~ 1.00)
 CIDetectorTracking: 是否開啟面部追蹤 TRUE 或 FALSE
 CIDetectorMaxFeatureCount: 設置返回矩形特征的最多個數 1 ~ 256 默認值為1
 CIDetectorNumberOfAngles: 設置角度的個數 1, 3, 5, 7, 9, 11
 CIDetectorImageOrientation: 識別方向
 CIDetectorEyeBlink: 眨眼特征
 CIDetectorSmile: 笑臉特征
 CIDetectorFocalLength: 每幀焦距
 CIDetectorAspectRatio: 矩形寬高比
 CIDetectorReturnSubFeatures: 文本檢測器是否應該檢測子特征，默認值是否
 */
 let features = detector?.features(in: ciimage, options: nil)

 // 遍歷出二維碼
 for item in features! where item.isKind(of: CIQRCodeFeature.self) {
 print((item as! CIQRCodeFeature).messageString ?? "")
 }
 }