Collection view getting nil while reloading data

Question

I have collectionView where I am displaying some images, initially from setup collectionview method everything is working fine.

@IBOutlet weak var collectionView: UICollectionView!

func setupCollectionView(){
    DispatchQueue.main.async {
        self.collectionView.delegate = self
        self.collectionView.dataSource = self
    }
    self.collectionView.register(UINib(nibName: "WallPapersCell", bundle: nil), forCellWithReuseIdentifier: "WallPapersCell")
}

Here comes the problem, whenever there is change in array I am reloading the data but collectionView getting nil hence collectionView.reloadData() is not getting called. What could be the reason? Am I missing something?

private var imagePathArray = [String](){
    didSet {
        print("did set")

        if let collectionView = self.collectionView {
            collectionView.reloadData()
        }
    }
}

func loadVideoWithVideoURL(_ videoURL: URL) {
        print("load video url \(videoURL)")
       // displayImageView.livePhoto = nil
        let asset = AVURLAsset(url: videoURL)
        let generator = AVAssetImageGenerator(asset: asset)
        generator.appliesPreferredTrackTransform = true
        let time = NSValue(time: CMTimeMakeWithSeconds(CMTimeGetSeconds(asset.duration)/2, preferredTimescale: asset.duration.timescale))
        generator.generateCGImagesAsynchronously(forTimes: [time]) { [weak self] _, image, _, _, _ in
            if let image = image, let data = UIImage(cgImage: image).pngData() {
                let urls = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
                let uniqueImageName = videoURL.deletingPathExtension().lastPathComponent
                print("/\(uniqueImageName).JPG")
                let imageURL = urls[0].appendingPathComponent("\(uniqueImageName).jpg")
                try? data.write(to: imageURL, options: [.atomic])
                print("Load image url \(imageURL)")
                let image = imageURL.path
                let mov = videoURL.path
                print("image path \(image) and mov path\(mov)")
                let output = FilePaths.VidToLive.livePath

                print(output)
                let assetIdentifier = UUID().uuidString
                print(output)
                if FileManager.default.fileExists(atPath: output + "/LiveWallpapers"){
                    print("exits")
                }else{
                    self?.createLiveWallpapersDirectoryIfNotExists(output: output)
                    print("live wallpapers folder doesnot exists in caches directory")
                }
                if FileManager.default.fileExists(atPath: output + "/LiveWallpapers/\(uniqueImageName).JPG"){
                    print("exits")
                    return
                }

                JPEG(path: image).write(output + "/LiveWallpapers/\(uniqueImageName).JPG",
                    assetIdentifier: assetIdentifier)
                QuickTimeMov(path: mov).write(output + "/LiveWallpapers/\(uniqueImageName).MOV",
                    assetIdentifier: assetIdentifier)
                self?.imagePathArray.append(output + "/LiveWallpapers/\(uniqueImageName).JPG")

                self?.videoPathArray.append(output + "/LiveWallpapers/\(uniqueImageName).MOV")

// here it is getting failed
                self?.exportLivePhoto(cachePath: "/LiveWallpapers/\(uniqueImageName)")

            }
        }
    }

This functions is getting failed when i am trying to record the video and trying to pair the video and photo. The operation couldn't be completed. (Cocoa error -1.) The operation couldn't be completed. (Cocoa error -1.) this error i am getting hence getting failed.

 func exportLivePhoto (cachePath : String) {
        PHPhotoLibrary.shared().performChanges({ () -> Void in
            let creationRequest = PHAssetCreationRequest.forAsset()
            let options = PHAssetResourceCreationOptions()


            creationRequest.addResource(with: PHAssetResourceType.pairedVideo, fileURL: URL(fileURLWithPath: "\(cachePath).MOV"), options: options)
            creationRequest.addResource(with: PHAssetResourceType.photo, fileURL: URL(fileURLWithPath:"\(cachePath).JPG"), options: options)

        }, completionHandler: { (success, error) -> Void in
            if !success {
                NSLog("export live error" + (error?.localizedDescription)!)
            }
        })
    }

Any suggestions ?

Thanks in Advance !!

Answer 1

• Make sure that your collectionView IBOutlet is connected and setupCollectionView() is called before imagePathArray .

• Also you can write code as below in your viewDidLoad rather than implementing setupCollectionView() method:

   override func viewDidLoad() { super.viewDidLoad() self.collectionView.delegate = self self.collectionView.datasource = self self.collectionView.register(UINib(nibName: "WallPapersCell", bundle: nil), forCellWithReuseIdentifier: "WallPapersCell") } 

Answer 2

The question now references two issues. You should keep the scope of your question limited to a single issue.

For the collectionView issue:

It looks like you are referencing the collectionView from outside of the class. Unless it is initialized from nib, or storyboard it will not create the IBOutlet/IBAction connections.

UPDATE:

From the comments we determined that the VC is being used as a Singleton via a static property and that this will not load the nib and connect the outlets. I would advise to move the shared code into another class/service and use that where needed.

For the exportLiveVideo issue:

The path that you are passing is:

/LiveWallpapers/\\(uniqueImageName)

You need to pass the full path..

Change

self?.exportLivePhoto(cachePath: "/LiveWallpapers/\(uniqueImageName)")

to

self?.exportLivePhoto(cachePath: output + "/LiveWallpapers/\(uniqueImageName)")