Как заставить UIIImagePickerController обрезать квадратное изображение?

Я искал по всему, и я не нашел твердого решения. Спасибо

var imagePickerController: UIImagePickerController = UIImagePickerController();
imagePickerController.allowsEditing = true;
imagePickerController.delegate = self;
imagePickerController.sourceType = sourceType;



func imagePickerController(picker: UIImagePickerController, didFinishPickingImage image: UIImage!, editingInfo: [NSObject : AnyObject]!) {
    profilePictureSelected = true;

    profilePictureImageView.image = image;

    picker.dismissViewControllerAnimated(true, completion: nil);
}