Hi 100DaysOfSwift Maniacs :)

I've faced a problem with second challenge in which we need to pass a name of a chosen filter and change a button's title. Probably it's very simple but maybe anyone could point out where I can pass this name ? I've tried some solutions but none of them worked...

 @IBAction func changeFilter(_ sender: Any) {
    let ac = UIAlertController(title: "Choose filter", message: nil, preferredStyle: .actionSheet)
    ac.addAction(UIAlertAction(title: "CIBumpDistortion", style: .default, handler: setFilter))
    ac.addAction(UIAlertAction(title: "CIGaussianBlur", style: .default, handler: setFilter))
    ac.addAction(UIAlertAction(title: "CIPixellate", style: .default, handler: setFilter))
    ac.addAction(UIAlertAction(title: "CISepiaTone", style: .default, handler: setFilter))
    ac.addAction(UIAlertAction(title: "CITwirlDistortion", style: .default, handler: setFilter))
    ac.addAction(UIAlertAction(title: "CIUnsharpMask", style: .default, handler: setFilter))
    ac.addAction(UIAlertAction(title: "CIVignette", style: .default, handler: setFilter))
    ac.addAction(UIAlertAction(title: "Cancel", style: .cancel))
    present(ac, animated: true)
  }

I need to pass chosen title from UIAlertAction 'title' to change title of a button

Thank you in advance.

So, the setFilter function should have a signature somewhat like this, right?

func setFilter(action: UIAlertAction) {...

The UIAlertAction here is the button that you press, which has the name of the filter as its title. So, all you need to do is get the title from the button and set it as the other button's title.

selectFilterButton.setTitle(action.title, for: .normal)

That was first thing that I've tried however this doesn't work... I added Outlet for this button:

  @IBOutlet var imageView: UIImageView!
  @IBOutlet var intensity: UISlider!
  @IBOutlet var changeFilterOutlet: UIButton!

and added setTitle within setFilter function:

 private func setFilter(action: UIAlertAction){
    guard currentImage != nil else {return}
    guard let actionTitle = action.title else {return}
    currentFilter = CIFilter(name: actionTitle)
    changeFilterOutlet.setTitle(action.title, for: .normal)
    let beginImage = CIImage(image: currentImage)
    currentFilter.setValue(beginImage, forKey: kCIInputImageKey)
    applyProcessing()
  }

Unfortunately title is not changing when I'm tapping on filter....

AAAA. I know what caused that problem.... I was trying to change button's title after guard let image without choosing an image....

func setFilter(action: UIAlertAction){
    guard currentImage != nil else {return}
    guard let actionTitle = action.title else {return}
    currentFilter = CIFilter(name: actionTitle)
    changeFilterOutlet.setTitle(action.title, for: .normal)
    let beginImage = CIImage(image: currentImage)
    currentFilter.setValue(beginImage, forKey: kCIInputImageKey)
    applyProcessing()
  }

Solution was to place changeFilterOutlet.setTitle(action.title, for: .normal) before guard let statement. I this case I'm able to change button's name even when image is not chosen!

func setFilter(action: UIAlertAction){
    changeFilterOutlet.setTitle(action.title, for: .normal)
    guard currentImage != nil else {return}
    guard let actionTitle = action.title else {return}
    currentFilter = CIFilter(name: actionTitle)
    let beginImage = CIImage(image: currentImage)
    currentFilter.setValue(beginImage, forKey: kCIInputImageKey)
    applyProcessing()
  }