ViewController.swift

private let metadataStorage = MetadataStorage()
private lazy var metadataProvider = LPMetadataProvider()
private weak var linkView: LPLinkView?
    
@IBAction func loadPreview(_ sender: UIButton) {
    if let text = textField.text, let url = URL(string: text) {
        // Avoid fetching LPLinkMetadata every time and archieve it disk
        if let metadata = metadataStorage.metadata(for: url) {
            linkView?.metadata = metadata
            return
        }
        metadataProvider.startFetchingMetadata(for: url) { [weak self] (metadata, error) in
            if let error = error {
                print(error)
            }
            else if let metadata = metadata {
                DispatchQueue.main.async { [weak self] in
                    self?.metadataStorage.store(metadata)
                    self?.linkView?.metadata = metadata
                }
            }
        }
    }
}