Swift https POST request for the PlantNet API - swift

Question

Currently I'm trying to program an https post request for the Plant Net API (https://my.plantnet.org/account/doc#) in Swift. I want to have one to five images inside my https post request and each image has as parameter organ (in my case this is always "leaf"). When I try to run my application, I get the error code 400 "Invalid multipart payload format". I'm not sure how I can solve this problem.
//
// PlantRecognition.swift
// Happy Plant
//
// Insert several images of the same plant (maximum of 5) and get the result list
//
import Foundation
import UIKit
class PlantRecognition {
//List with images of the plant to be recognized
var imageList: [UIImage] = []
//Api key for the plant net access
var API_KEY: String = "MY_API_KEY"
var plantNetURL: String = ""
init() {
//Set plant net url after class initialization
plantNetURL = "https://my-api.plantnet.org/v2/identify/all?api-key{\(API_KEY)}"
}
func recognizeImages(images: [UIImage]) {
//Try to create the api endpoint url
guard let apiEndpoint = URL(string: "https://my-api.plantnet.org/v2/identify/all?api-key=\(API_KEY)") else {print("Error creating api endpoint"); return }
//Convert the UIImages to jpeg
let imagesJPG = convertImagesToJPEG(images: images)
//Create url request
var request = URLRequest(url: apiEndpoint)
//Set the http method to post (local images)
request.httpMethod = "POST"
//Create boundary which marks the start/end of the request body
let boundary = "Boundary-\(UUID().uuidString)"
//Set value for our specific http header field
request.setValue("multipart/form-data; boundary=\(boundary)", forHTTPHeaderField: "Content-Type")
//Set the mime type to jpg (we will convert our UIImages to jpg)
let mimeType = "image/jpg"
//Create http body
var body = Data()
let boundaryPrefix = " — \(boundary)\r\n"
//Add the parameter to the body (Currently just leaf recognition is possible)
body.append("--\(boundaryPrefix)\r\n")
body.append("Content-Disposition: form-data; name=\"organs\r\n\r\n")
body.append("leaf\r\n")
//Add the images to the body
var filename = String()
for (index,data) in imagesJPG.enumerated(){
filename = "image\(index)"
body.append(boundaryPrefix)
body.append("Content-Disposition: form-data; name=\"image[]\"; filename=\"\(filename)\"\r\n")
body.append("Content-Type: \(mimeType)\r\n\r\n")
body.append(data)
body.append("\r\n")
}
body.append("--\(boundary)--\r\n")
//Post the request
let session = URLSession.shared
session.dataTask(with: request) { (data, response, error) in
if let response = response {
print(response)
}
if let data = data {
do {
let json = try JSONSerialization.jsonObject(with: data, options: [])
print(json)
} catch {
print(error)
}
}
}.resume()
}
func convertImagesToJPEG(images: [UIImage]) -> [Data] {
var dataArray = [Data]()
for i in images {
if let data = i.jpegData(compressionQuality: 1.0) {
dataArray.append(data)
}
}
return dataArray
}
}
extension Data {
mutating func append(_ string: String) {
if let data = string.data(using: .utf8) {
append(data)
}
}
}