[Swift] unable to handle response header and statusCode

Description

In swift template, generated source code only considered about response body as below, but we'd like to use not only body, but also header and statusCode in response.

open class func {{operationId}}({{#allParams}}{{paramName}}: {{#isEnum}}{{#isContainer}}{{{dataType}}}{{/isContainer}}{{^isContainer}}{{{datatypeWithEnum}}}_{{operationId}}{{/isContainer}}{{/isEnum}}{{^isEnum}}{{{dataType}}}{{/isEnum}}{{^required}}? = nil{{/required}}{{#hasMore}}, {{/hasMore}}{{/allParams}}{{#hasParams}}, {{/hasParams}}completion: @escaping ((_ {{#returnType}}data: {{{returnType}}}?,_ {{/returnType}}error: Error?) -> Void)) {
    {{operationId}}WithRequestBuilder({{#allParams}}{{paramName}}: {{paramName}}{{#hasMore}}, {{/hasMore}}{{/allParams}}).execute { (response, error) -> Void in
        completion({{#returnType}}response?.body, {{/returnType}}error);
    }
}

This template will be generated as below.

open class func testClientModel(body: Client, completion: @escaping ((_ data: Client?,_ error: Error?) -> Void)) {
  testClientModelWithRequestBuilder(body: body).execute { (response, error) -> Void in
    completion(response?.body, error);
  }
}

Swagger-codegen version

2.3.0-SNAPSHOT

Swagger declaration file content or url

Command line used for generation

Steps to reproduce

Related issues/PRs

Suggest a fix/enhancement

To keep codegen more generic, we should change mustache as below. (change response?.body to response )

    open class func {{operationId}}({{#allParams}}{{paramName}}: {{#isEnum}}{{#isContainer}}{{{dataType}}}{{/isContainer}}{{^isContainer}}{{{datatypeWithEnum}}}_{{operationId}}{{/isContainer}}{{/isEnum}}{{^isEnum}}{{{dataType}}}{{/isEnum}}{{^required}}? = nil{{/required}}{{#hasMore}}, {{/hasMore}}{{/allParams}}{{#hasParams}}, {{/hasParams}}completion: @escaping ((_ {{#returnType}}data: Response<{{{returnType}}}>?,_ {{/returnType}}error: Error?) -> Void)) {
        {{operationId}}WithRequestBuilder({{#allParams}}{{paramName}}: {{paramName}}{{#hasMore}}, {{/hasMore}}{{/allParams}}).execute { (response, error) -> Void in
            completion({{#returnType}}response, {{/returnType}}error);
        }
    }

PromiseKit and RxSwift are also followed with above.

As follow my suggestion, the output will be as below.

    open class func testClientModel(body: Client, completion: @escaping ((_ data: Response<Client>?,_ error: Error?) -> Void)) {
        testClientModelWithRequestBuilder(body: body).execute { (response, error) -> Void in
            completion(response, error);
        }
    }

//usage:
API.testClientModel(body: client)
  .subscribe(onNext: { response in
     print(response.body) // T? (generated as Model)
     print(response.header) // [String : String]
     print(response.statusCode)
  }, onError: { error in
    print(error.localizedDescription)
  }).disposed(by: disposeBag)

Start with the Swift template that generates the completion callback and compare its current response?.body handling with the proposed Response<...> return. Check the corresponding PromiseKit and RxSwift output mentioned in the issue. Done means generated Swift clients expose the response body, headers, and status code rather than only the body.