Type of expression is ambiguous without more context in Alamofire.upload swift 3

Question

Updated Alamofire 4.0.0 does not mention how to put Httpmethod & Httpheaders in upload with multipartFormData. That's why I google and found solution in that stackoverflow question. But the problem is I did same as that answer then got following error message and building is failed. Please help me how to solve it.

Type of expression is ambiguous without more context

Here is my coding:

let URL = try! URLRequest(url: Config.imageUploadURL, method: .post, headers: headers)

Alamofire.upload(
    multipartFormData: { multipartFormData in
        multipartFormData.append(self.imageData, withName: "image", fileName: "file.png", mimeType: "image/png")
    },
    to: URL,
    encodingCompletion: { encodingResult in
        switch encodingResult {
        case .success(let upload, _, _):
            upload.responseJSON { response in
                if((response.result.value) != nil) {

                } else {

                }
            }
        case .failure( _):

        }
    }
)

Answer 1

Alamofire.upload(multipartFormData:to:encodingCompletion:) takes a URLConvertible for the to: argument. Instead, you should use Alamofire.upload(multipartFormData:with:encodingCompletion:) which takes a URLRequestConvertible for its with: argument.

I think your argument name of URL that is the same as the type URL() helps in creating strange compiler errors.

The following compiles for me:

let url = try! URLRequest(url: URL(string:"www.google.com")!, method: .post, headers: nil)

Alamofire.upload(
    multipartFormData: { multipartFormData in
        multipartFormData.append(Data(), withName: "image", fileName: "file.png", mimeType: "image/png")
    },
    with: url,
    encodingCompletion: { encodingResult in
        switch encodingResult {
        case .success(let upload, _, _):
            upload.responseJSON { response in
                if((response.result.value) != nil) {

                } else {

                }
            }
        case .failure( _):
            break
        }
    }
)