Swift中的HTTP POST请求畸形的Form-Data主体？

Question

我正在编写HTTP POST请求，以通过Facebook Graph API上传媒体（图片）将其上传到WhatsApp，并在其文档中格式化如下：

curl -X POST \
  'https://graph.facebook.com/v13.0/FROM_PHONE_NUMBER_ID/media' \
  -H 'Authorization: Bearer ACCESS_TOKEN' \
  -F 'file=@/local/path/file.jpg;type=image/jpeg' 
  -F 'messaging_product=whatsapp'

我有正确的信息，因为它在构造Postman的请求并保留时可以工作身体为形式。

这是Postman成功请求的原始日志（我已经删除了访问令牌，边界字符串和图像的二进制文件）：

POST /v13.0/111101394989431/media HTTP/1.1
Authorization: Bearer <token>
User-Agent: PostmanRuntime/7.26.1
Accept: */*
Cache-Control: no-cache
Postman-Token: d84bb595-a5a5-4f42-b286-46dfef5828e5
Host: graph.facebook.com
Accept-Encoding: gzip, deflate, br
Connection: keep-alive
Content-Type: multipart/form-data; boundary=<boundary-string>
Content-Length: 65306
--<boundary-string>
Content-Disposition: form-data; name="messaging_product"

whatsapp
--<boundary-string>
Content-Disposition: form-data; name="file"; filename="gm.jpeg"

<gm.jpeg>
--<boundary-string>--

这是Swift中的我的网络代码，为您的利益发表了评论。请查看CreateBody方法（在底部），这可能是格式较差的HTTP主体的来源，因此是400个错误。

//
//  WhatsappMediaAPIClient.swift
//  SnapShare
//
//  Created by Faraz Malik on 04/07/2022.
//

import Foundation
import UIKit

enum WhatsappImageError: Error {
    case requestFailed
    case responseUnsuccessful(statusCode: Int)
    case jsonParsingFailure
    case invalidURL
}

class WhatsappImageAPIClient {
    private let whatsappPhoneID = "<phone-ID>"
    
    // returns the base url string with the phone ID attached, when accessed
    private lazy var baseUrlString: String = {
        return "https://graph.facebook.com/v13.0/\(whatsappPhoneID)/media"
    }()
    
    let decoder = JSONDecoder()
    let session: URLSession
    
    init(withConfiguration configuration: URLSessionConfiguration = .default) {
        self.session = URLSession(configuration: configuration)
    }
    
    // MARK: Typealiases
    
    typealias WhatsappImageCompletionHandler = (WhatsappImage?, Error?) -> Void
    
    
    // MARK: Post Whatsapp Image
    // called to upload image to WhatsApp via Facebook Graph API
    // calls escaping completion handler to pass up data or error appropriately.
    public func postWhatsappImage(withAccessToken accessToken: String, imageData: Data, completionHandler completion: @escaping WhatsappImageCompletionHandler) {
        
        // creates URL from URL string
        guard let url = URL(string: baseUrlString) else {
            completion(nil, WhatsappImageError.invalidURL)
            return
        }
        
        // gets a boundary string to work with for this request
        let boundaryString = getBoundaryString()
        
        // creates a request
        var request = URLRequest(url: url)
        request.httpMethod = "POST"
        
        // adds access token and content type as fields in the header
        request.addValue("Bearer \(accessToken)", forHTTPHeaderField: "Authorization")
        request.setValue("multipart/form-data; boundary=\(boundaryString)", forHTTPHeaderField: "Content-Type")
        
        // required parameter for form-data in body
        let parameters = ["messaging_product": "whatsapp", "type": "image/jpeg"]
        
        // gets and assigns body, formatted to form-data with parameters and image data
        let requestData = createBody(withParameters: parameters, imageData: imageData, boundaryString: boundaryString)
        request.httpBody = requestData
        
        // sends request asynchronously (i.e. background)
        let session = URLSession(configuration: .default)
        let task = session.dataTask(with: request) { data, response, error in
            DispatchQueue.main.async {
                // if we got a response
                if let data = data {
                    // if we can cast response as HTTPURLResponse
                    guard let httpResponse = response as? HTTPURLResponse else {
                        completion(nil, WhatsappImageError.requestFailed)
                        return
                    }
                    
                    // if it's ok
                    if httpResponse.statusCode == 200 {
                        do {
                            // try to decode it
                            let whatsappImageID = try self.decoder.decode(WhatsappImage.self, from: data)
                            // pass up to completion handler
                            completion(whatsappImageID, nil)
                        } catch {
                            // pass up to completion handler
                            completion(nil, WhatsappImageError.jsonParsingFailure)
                        }
                    } else if httpResponse.statusCode == 400 {
                        // print message for inspection
                        print("\n\n\n\n")
                        print(String(decoding: data, as: UTF8.self))
                        print("\n\n\n\n")
                        // pass up to completion handler
                        completion(nil, WhatsappImageError.responseUnsuccessful(statusCode: httpResponse.statusCode))
                    } else {
                        // pass up to completion handler
                        completion(nil, WhatsappImageError.responseUnsuccessful(statusCode: httpResponse.statusCode))
                    }
                    
                } else if let error = error {
                    // pass up error
                    completion(nil, error)
                }
            }
        }
        
        task.resume()
    }
    
    // creates body data (error could very well lie here because 400 bad request means body is malformed)
    // please give this a look (image is always jpeg)
    private func createBody(withParameters parameters: [String: String], imageData: Data, boundaryString: String) -> Data {
        
        let body = NSMutableData()
        let boundaryPrefix = "--\(boundaryString)\r\n"
        let filename = "upload.jpg"
                
        for (key, value) in parameters {
            body.append(boundaryPrefix.data(using: .utf8)!)
            body.append("Content-Disposition: form-data; name=\"\(key)\"\r\n".data(using: .utf8)!)
            body.append("\(value)\r\n".data(using: .utf8)!)
        }
        
        body.append(boundaryPrefix.data(using: .utf8)!)
        body.append("Content-Disposition: form-data; name=\"file\"; filename=\"\(filename)\"\r\n".data(using: .utf8)!)
        body.append("Content-Type: image/jpeg\r\n".data(using: .utf8)!)
        body.append(imageData)
        body.append("\r\n".data(using: .utf8)!)
        body.append("--".appending(boundaryString.appending("--\r\n")).data(using: .utf8)!)
        
        return body as Data
    }
    
    private func getBoundaryString() -> String {
        let boundary = "\(UUID().uuidString)"
        return boundary
    }
}

希望您能发现出了什么问题，因为我已经使用了2天了，而与Postman相比，我无法弄清楚我在发送Swift请求时做的不同之处 - 使它失败的差异。