ios - 无法将类型 '(_) -> ()' 的值转换为预期的参数类型 '((Bool, Error?) -> Void)?'

Question

拜托，我需要帮助解决问题，我将 Swift 3 的语法更改为 Swift 4，现在我在识别所有错误时遇到很多问题。最后一行中的函数 savePhoto 出现错误。, completionHandler: { _在

func takePhoto(_ previewLayer: AVCaptureVideoPreviewLayer, location: CLLocation?, completion: (() -> Void)? = nil) {
    guard let connection = stillImageOutput?.connection(with: AVMediaType.video) else { return }

    connection.videoOrientation = Helper.videoOrientation()

    queue.async {
      self.stillImageOutput?.captureStillImageAsynchronously(from: connection) {
        buffer, error in

        guard let buffer = buffer, error == nil && CMSampleBufferIsValid(buffer),
          let imageData = AVCaptureStillImageOutput.jpegStillImageNSDataRepresentation(buffer),
          let image = UIImage(data: imageData)
          else {
            DispatchQueue.main.async {
              completion?()
            }
            return
        }

        self.savePhoto(image, location: location, completion: completion)
      }
    }
  }

  func savePhoto(_ image: UIImage, location: CLLocation?, completion: (() -> Void)? = nil) {
    PHPhotoLibrary.shared().performChanges({
      let request = PHAssetChangeRequest.creationRequestForAsset(from: image)
      request.creationDate = Date()
      request.location = location
    }, completionHandler: { _ in
        DispatchQueue.main.async {
          completion?()
        }
    })
  }

Answer 1

重写为:

}, completionHandler: { (_, _) in

根据 documentation ，performChanges(_:completionHandler:) 中的完成处理程序接受两个参数，而不仅仅是一个。 _ in，你用过的，只是一个单一参数的占位符。