Block in Block

block.swift

class Test {
  let networkClient: NetworkClient
  let jsonSerilizer: JSONSerilizer
  let logger: Logger
  
  func run(completion: @escaping (Result) -> Void) {
    let url: URL = URL(...)
    logger.log("send request to \(url)"
    networkClient.request(url) { [weak self] response, error in
      guard let self = self else { return }
      self.logger.log("processing response of \(url)"
      self.jsonSerilizer.process(response) { [weak self] result in
        guard let self = self else { return }
        self.logger.log("processing response of \(url) finished")
        completion(result)
      }
    }
  }
}

On line 12, we should use [weak self] to avoid retain cycle, or we don't need?

On line 10, if we write guard let strongSelf = self, then on line 12, should we use [weak strongSelf] or [weak self]?