Swift app crashes when uploading image to firebase

Question

I'm trying to get the thumbnail of the video I have selected.

It seems like it does create the thumbnail but it crashes when uploading it to firebase

It crashes at thumbnailStorageRef I believe.

Here's the relevant code :

guard let imagePickerUrl = info[UIImagePickerControllerMediaURL] as? URL else { return }
let videoUrl = imagePickerUrl

// Generate image thumbnail.

let asset: AVAsset = AVAsset(url: videoUrl as URL)
let imageGenerator = AVAssetImageGenerator(asset: asset)
imageGenerator.appliesPreferredTrackTransform = true
var time = asset.duration
time.value = min(time.value, 3)

do {
    let thumbnailImage = try imageGenerator.copyCGImage(at: time , actualTime: nil)
    let image = UIImage(cgImage: thumbnailImage)
    let imageData = UIImagePNGRepresentation(image)!

    let thumbnailStorageRef = FIRStorage.storage().reference()
    thumbnailStorageRef.child("thumbnails/" + randomString(length: 20) + ".png")

    thumbnailStorageRef.put(imageData, metadata: nil, completion: { (thumbnailMeta, error) in
        if error != nil {
            print("An error has occured while uploading thumbnail:",error ?? "")
        } else {
            print("Thumbnail upload to database was successfull", thumbnailMeta?.downloadURL() ?? "")
        }
    })
} catch {
    print("An error has occurred while making thumbnail:")
}

When crashing the error console says:

2017-08-11 17:19:08.656 Koala[17914:491998] * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '* -[__NSPlaceholderDictionary initWithObjects:forKeys:count:]: attempt to insert nil object from objects[1]' *** First throw call stack:

I don't know what this error message is trying to say, maybe that the image trying to upload is nil? I'm not sure.

Answer 1

It looks like you forgot to use the child storage node you just created. As such, try replacing this code:

thumbnailStorageRef.child("thumbnails/" + randomString(length: 20) + ".png")
thumbnailStorageRef.put(imageData, metadata: nil, completion: ...

with this instead:

let imageRef = thumbnailStorageRef.child("thumbnails/" + randomString(length: 20) + ".png")
imageRef.put(imageData, metadata: nil, completion: ...

This change should fix your current issue ;)