Face detection In swift

bhavuk chawla

6 July 2023

By using Vision framework you can do many things like detection of faces, face features, object tracking, and others.

In this blog, we will take a look at how we can detect a face from an image. Following are the steps to perform face detection

First, you need an image from which you can detect a face from an image this is taken from the camera or a Photos from your iPhone, you can use for this UIImagePickerController

let picker = UIImagePickerController()
picker.delegate = self
let alert = UIAlertController(title: nil, message: nil, preferredStyle: .actionSheet)
if UIImagePickerController.isSourceTypeAvailable(.camera) {
    alert.addAction(UIAlertAction(title: "Camera", style: .default, handler: {action in
        picker.sourceType = .camera
        self.present(picker, animated: true, completion: nil)
    }))
}
alert.addAction(UIAlertAction(title: "Photo Library", style: .default, handler: { action in
    picker.sourceType = .photoLibrary
    self.present(picker, animated: true, completion: nil)
}))
alert.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: nil))
alert.popoverPresentationController?.sourceRect = self.view.frame
self.present(alert, animated: true, completion: nil)

let picker = UIImagePickerController()

picker.delegate = self

let alert = UIAlertController(title: nil, message: nil, preferredStyle: .actionSheet)

if UIImagePickerController.isSourceTypeAvailable(.camera) {

alert.addAction(UIAlertAction(title: "Camera", style: .default, handler: {action in

picker.sourceType = .camera

self.present(picker, animated: true, completion: nil)

}))

}

alert.addAction(UIAlertAction(title: "Photo Library", style: .default, handler: { action in

picker.sourceType = .photoLibrary

self.present(picker, animated: true, completion: nil)

}))

alert.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: nil))

alert.popoverPresentationController?.sourceRect = self.view.frame

self.present(alert, animated: true, completion: nil)

Then use these delegate methods to get an image:

extention ViewController: UIImagePickerControllerDelegate, UINavigationControllerDelegate {
    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {
        dismiss(animated: true, completion: nil)
        self.image = info[UIImagePickerControllerOriginalImage] as! UIImage

    }
}

extention ViewController: UIImagePickerControllerDelegate, UINavigationControllerDelegate {

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {

dismiss(animated: true, completion: nil)

self.image = info[UIImagePickerControllerOriginalImage] as! UIImage

}

After fetching the image then you have to use that for detecting a face CIDetector find an example below for detecting a face.

let imageOptions =  NSDictionary(object: NSNumber(value: 5) as NSNumber, forKey: CIDetectorImageOrientation as NSString)
let personciImage = CIImage(cgImage: image.cgImage!)
let accuracy = [CIDetectorAccuracy: CIDetectorAccuracyHigh]
let faceDetector = CIDetector(ofType: CIDetectorTypeFace, context: nil, options: accuracy)
let faces = faceDetector?.features(in: personciImage, options: imageOptions as? [String : AnyObject])

if let face = faces?.first as? CIFaceFeature {
    print("found bounds are \(face.bounds)")
    let alert = UIAlertController(title: "Say Cheese!", message: "We detected a face!", preferredStyle: UIAlertController.Style.alert)
//            alert.addAction(UIAlertAction(title: "OK", style: UIAlertAction.Style.default, handler: nil))
    let confirmAction = UIAlertAction(title: "OK", style: .default) { [weak alert] _ in

    }
    alert.addAction(confirmAction)
    let cancelAction = UIAlertAction(title: "Cancel", style: .cancel, handler: nil)
    alert.addAction(cancelAction)
} else {
     let alert = UIAlertController(title: "No Face!", message: "No face was detected", preferredStyle: UIAlertController.Style.alert)
        alert.addAction(UIAlertAction(title: "OK", style: UIAlertAction.Style.default, handler: nil))
        self.present(alert, animated: true, completion: nil)
}

let imageOptions = NSDictionary(object: NSNumber(value: 5) as NSNumber, forKey: CIDetectorImageOrientation as NSString)

let personciImage = CIImage(cgImage: image.cgImage!)

let accuracy = [CIDetectorAccuracy: CIDetectorAccuracyHigh]

let faceDetector = CIDetector(ofType: CIDetectorTypeFace, context: nil, options: accuracy)

let faces = faceDetector?.features(in: personciImage, options: imageOptions as? [String : AnyObject])

if let face = faces?.first as? CIFaceFeature {

print("found bounds are \(face.bounds)")

let alert = UIAlertController(title: "Say Cheese!", message: "We detected a face!", preferredStyle: UIAlertController.Style.alert)

// alert.addAction(UIAlertAction(title: "OK", style: UIAlertAction.Style.default, handler: nil))

let confirmAction = UIAlertAction(title: "OK", style: .default) { [weak alert] _ in

}

alert.addAction(confirmAction)

let cancelAction = UIAlertAction(title: "Cancel", style: .cancel, handler: nil)

alert.addAction(cancelAction)

} else {

let alert = UIAlertController(title: "No Face!", message: "No face was detected", preferredStyle: UIAlertController.Style.alert)

alert.addAction(UIAlertAction(title: "OK", style: UIAlertAction.Style.default, handler: nil))

self.present(alert, animated: true, completion: nil)

}

By using the help CIFaceFeature you can also detect that smiling face or face’s eye positioning and many others.

    if face.hasSmile {
        print("face is smiling");
    }
    
    if face.hasLeftEyePosition {
        print("Left eye bounds are \(face.leftEyePosition)")
    }
    
    if face.hasRightEyePosition {
        print("Right eye bounds are \(face.rightEyePosition)")
    }

if face.hasSmile {

print("face is smiling");

}

if face.hasLeftEyePosition {

print("Left eye bounds are \(face.leftEyePosition)")

}

if face.hasRightEyePosition {

print("Right eye bounds are \(face.rightEyePosition)")

}

I hope you enjoyed this, please let me know in the comments how did it go and if there are things that can be improved. Thanks for tuning in once again!