你能比较几乎相同的图片吗？

Question

下面的代码让我用相机拍照并将其放在图像视图中。标签中也会出现一些文字。

例如：我在包括我自己在内的几个朋友的assets.xcassets中有一些图片。当我从自己拍照时，应用程序应扫描所有图片并说：“这张照片上的人就是我”。

我如何比较图片，让我们说75％相等？

var imagePicker: UIImagePickerController!

@IBOutlet weak var ImageView: UIImageView!
@IBOutlet weak var lblText: UILabel!

override func viewDidLoad() {
    super.viewDidLoad()

}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

@IBAction func takeImage(sender: AnyObject) {

    imagePicker = UIImagePickerController()
    imagePicker.delegate = self
    imagePicker.sourceType = .Camera
    presentViewController(imagePicker, animated: true, completion: nil)

}

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

    imagePicker.dismissViewControllerAnimated(true, completion: nil)
    ImageView.image = info[UIImagePickerControllerOriginalImage] as? UIImage

    lblText.text = "The person on this picture is *name person on picture*"

}

@IBAction func resetImage(sender: AnyObject) {

    ImageView.image = nil
    lblText.text = nil
}