UIImageWriteToSavedPhotosAlbum Selector Syntax Issue

Question

Trying hard to get UIImageWriteToSavedPhotosAlbum to work in swift https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIKitFunctionReference/index.html#//apple_ref/c/func/UIImageWriteToSavedPhotosAlbum

The documentation is sadly ONLY in objective C.

Here is my code:

func saveImage()
{
  UIImageWriteToSavedPhotosAlbum(uiimage, self, "saveImageComplete:::", nil)
}

func saveImageComplete(image:UIImage,err:NSError,context:UnsafePointer<()>)
{
  loadLastPhotoIntoGalleryIcon()
}

But the problem is that it throws the NSInvalidArgumentException with an unrecognized selector:

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', 
reason: 'app.PhotoEditor<0x14a1e400> does not respond to selector 
saveImageComplete:::'

Can you advise what is wrong with my syntax and how I properly specific this selector? From what I understand, each : represents 1 argument the method expects and since it has 3 parameters I gave it 3 :'s.

Thanks!

Answer 1

Above none work for Swift3. Try this for those who are struggling with Swift3 Syntax's

Action:

@IBAction func saveToPhotos(_ sender: AnyObject) {

    UIImageWriteToSavedPhotosAlbum(yourImageView.image!, self, #selector(image(_:didFinishSavingWithError:contextInfo:)), nil)
}

Target:

func image(_ image: UIImage, didFinishSavingWithError error: Error?, contextInfo: UnsafeRawPointer) {

    if error == nil {
        let ac = UIAlertController(title: "Saved!", message: "Image saved to your photos.", preferredStyle: .alert)
        ac.addAction(UIAlertAction(title: "OK", style: .default, handler: nil))
        present(ac, animated: true, completion: nil)
    } else {
        let ac = UIAlertController(title: "Save error", message: error?.localizedDescription, preferredStyle: .alert)
        ac.addAction(UIAlertAction(title: "OK", style: .default, handler: nil))
        present(ac, animated: true, completion: nil)
    }
}

Refer this link for more clarification https://www.hackingwithswift.com/read/13/5/saving-to-the-ios-photo-library

Answer 2

The correct UIImageWriteToSavedPhotosAlbum/selector code is here:

func onYesClicked(action:Int){
    // i'm using optional image here just for example
    if let image = getImage() {
        UIImageWriteToSavedPhotosAlbum(
            image, self,
            Selector("image:didFinishSavingWithError:contextInfo:"),
            nil)
    }
}

func image(
    image: UIImage!,
    didFinishSavingWithError error:NSError!,
    contextInfo:UnsafePointer<Void>)
{
    // process success/failure here
}

Here's the most up-to-date syntax, 2016

@IBAction func clickedSaveToUsersCameraRoll()
    {
    print("actually saving yourImage.image to the camera roll, 2016.")
    UIImageWriteToSavedPhotosAlbum(
        yourImage.image!, self,
        #selector(savedOK(_:didFinishSavingWithError:contextInfo:)),
        nil)
    }

func savedOK(
        image:UIImage!,
        didFinishSavingWithError error:NSError!,
        contextInfo:UnsafePointer<Void>)
    {
    print("Wrote photo ok")
    }

Answer 3

If your method were an Objective-C method, the selector would be something like "saveImageCompleteImage:err:context:". You need to remember that the parameters are part of the name in Objective-C, so "saveImageComplete:::" doesn't specify a method that could be called saveImageComplete(image:UIImage,err:NSError,context:UnsafePointer<()>) in Swift.

Answer 4

In Swift 4.x and 5.0:

UIImageWriteToSavedPhotosAlbum(imageToSave, self, #selector(saveImageComplete(image:err:context:)), nil)

Don't forget the @objc decorator in it's declaration:

@objc private func saveImageComplete(image:UIImage, err:NSError, context:UnsafeMutableRawPointer?) {
    
}