downloadURL returns nil

Question

I try to upload an Image to the Firebase Database, but every time I select a Picture and try to upload it, I get an error saying Thread+1: Fatal error: Unexpectedly found nil while unwrapping an Optional value

This error appeared after I updated firebase...

func save() {
    let newPostKey = ref.key
    // save jobImage
    if let imageData = jobImage?.jpegData(compressionQuality: 0.5) {
        let storage = Storage.storage().reference().child("jobImages/\(newPostKey!)")
        
            storage.putData(imageData, metadata: nil) { (metadata, error) in
            
                if error != nil{
                    print(error!)
                } else {
                    storage.downloadURL(completion: { (URL, error) in
                        if error != nil{
                            print(error!)
                            return
                        }
                        if URL != nil{
                            let postDictionary = [
                                "imageDownloadURL" : self.downloadURL!, //-> ERROR (Removing the '!' doesn't give any error, but then also no picture gets uploaded...)
                                "text" : self.text,
                            ] as [String : Any]
                            self.ref.setValue(postDictionary)
                        }
                    })
                }
            }
        }
    } 

I select the picture like this:

        let newJob = Job(text: jobTextView.text, jobImage: takenImage!)
        newJob.save()

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {

    self.dismiss(animated: true) { [weak self] in

        guard let image = info[UIImagePickerController.InfoKey.originalImage] as? UIImage else { return }
        //Setting image to your image view
        self!.takenImage = image
        self!.jobImage.image = self!.takenImage //-> The imageVIew gets filled with the takenImage, so I guess that nothings wrong there
        self!.changeImage.isHidden = false
        self!.addImage.isHidden = true
    }
}

EDIT:

var jobImage: UIImage?
var downloadURL: String?
var jobImage: UIImage?


init(text: String? = nil, jobImage: UIImage? = nil) {
    self.text = text!
    self.jobImage = jobImage
    ref = Database.database().reference().child("jobs").childByAutoId()
}

init(snapshot: DataSnapshot){
    ref = snapshot.ref
    if let value = snapshot.value as? [String : Any] {
        text = value["text"] as! String
        downloadURL = value["imageDownloadURL"] as? String
    }
}

Answer 1

You're not setting self.downloadURL anywhere, which means that it's nil and leads to the error when you try to unwrap it.

You can either set the self.downloadURL inside the callback:

storage.downloadURL(completion: { (URL, error) in
    if error != nil{
        print(error!)
        return
    }
    if URL != nil{
        self.downloadURL = URL
        let postDictionary = [
            "imageDownloadURL" : self.downloadURL!,
            "text" : self.text,
        ] as [String : Any]
        self.ref.setValue(postDictionary)
    }
})

Or you can directly pass the URL parameter into the database call:

"imageDownloadURL" : URL!