let task = session.downloadTaskWithRequest(request) { [weak self] //или unowned?
        (let location, let response, let error) in
    ...
    self?.error = error
    ...
    let task = session.downloadTaskWithRequest(request1) { [weak self] // нужно ли снова писать?
        (let location, let response, let error) in
      ...
      self?.error1 = error
      ...
    }
 }