如何在swift中将blob存储数据追加到multipart/form-data

import Foundation

func createMultipartFormDataRequest(url: URL, blobData: Data, fieldName: String, fileName: String, mimeType: String) -> URLRequest {
    var request = URLRequest(url: url)
    request.httpMethod = "POST"
    
    let boundary = UUID().uuidString
    let contentType = "multipart/form-data; boundary=\(boundary)"
    request.setValue(contentType, forHTTPHeaderField: "Content-Type")
    
    let body = NSMutableData()
    
    // 添加Blob数据
    body.append("--\(boundary)\r\n".data(using: .utf8)!)
    body.append("Content-Disposition: form-data; name=\"\(fieldName)\"; filename=\"\(fileName)\"\r\n".data(using: .utf8)!)
    body.append("Content-Type: \(mimeType)\r\n\r\n".data(using: .utf8)!)
    body.append(blobData)
    body.append("\r\n".data(using: .utf8)!)
    
    // 添加其他表单数据
    // body.append("--\(boundary)\r\n".data(using: .utf8)!)
    // body.append("Content-Disposition: form-data; name=\"key\"\r\n\r\n".data(using: .utf8)!)
    // body.append("value\r\n".data(using: .utf8)!)
    
    body.append("--\(boundary)--\r\n".data(using: .utf8)!)
    
    request.httpBody = body as Data
    
    return request
}

// 使用示例
let blobData = "Hello, World!".data(using: .utf8)!
let url = URL(string: "https://example.com/upload")!
let request = createMultipartFormDataRequest(url: url, blobData: blobData, fieldName: "file", fileName: "example.txt", mimeType: "text/plain")

let task = URLSession.shared.dataTask(with: request) { (data, response, error) in
    if let error = error {
        print("Error: \(error)")
    } else if let data = data {
        let responseString = String(data: data, encoding: .utf8)
        print("Response: \(responseString ?? "")")
    }
}

task.resume()