ImageBatchLoader.swift

final class ImageBatchLoader {
  weak var delegate: ImageBatchLoaderDelegate?
    
  init(delegate: ImageBatchLoaderDelegate) {
    self.delegate = delegate
  }
    
  func start() {
    DispatchQueue.global().async {
      self.delegate?.imageLoader(self, didLoadBatch: [UIImage()])
    }
  }
}

protocol ImageBatchLoaderDelegate: AnyObject {
  func imageLoader(_ imageLoader: ImageBatchLoader, didLoadBatch batch: [UIImage])
}