Изменить
let longPressRecognizer = UILongPressGestureRecognizer(target: self, action: Selector(("longPressed:")))
UIImageWriteToSavedPhotosAlbum(ImageViewer.image!, self, Selector(("image:didFinishSavingWithError:contextInfo:")), nil)
на
let longPressRecognizer = UILongPressGestureRecognizer(target: self, action: #selector(longPressed(sender:)))
UIImageWriteToSavedPhotosAlbum(ImageViewer.image!, self, #selector(image(_:didFinishSavingWithError:contextInfo:)), nil)
Изменить didFinishSavingWithError
метод, подобный этому
@objc func image(_ image: UIImage, didFinishSavingWithError error: NSError?, contextInfo: UnsafeRawPointer) {
if let error = error {
print(error.localizedDescription)
} else {
print("image saved")
}
}