Swift调用Nordigen API设POST仍返回GET不允许错误求助

我尝试通过Nordigen API获取token，尽管在Swift代码中设置httpMethod为"POST"，但始终收到405错误，提示："Method "GET" not allowed"。我是Swift新手，推测遗漏了基础设置。

我的Swift代码如下：

import Foundation

let apiUrl = URL(string: "https://ob.nordigen.com/api/v2/token/new")!

let clientId = "your_client_id"
let clientSecret = "your_client_secret"
let requestBody: [String: Any] = [
    "client_id": clientId,
    "client_secret": clientSecret
]

let requestData = try! JSONSerialization.data(withJSONObject: requestBody)

var request = URLRequest(url: apiUrl)
request.httpMethod = "POST"
request.httpBody = requestData
request.setValue("application/json", forHTTPHeaderField: "Content-Type")

let task = URLSession.shared.dataTask(with: request) { (data, response, error) in
    if let data = data, let json = try? JSONSerialization.jsonObject(with: data, options: []) as? [String: Any] {
        print(json)
        if let accessToken = json["access"] as? String {
            print("Access Token: \(accessToken)")
        }
    }
}

task.resume()

按此代码执行，即便没有有效client id/secret，理应返回401错误“Authentication failed”，提示“ No active account found with the given credentials”。我用JavaScript测试该API可正常工作，代码如下：

var userid = "user id";
var userkey = "user key";

var raw = JSON.stringify({"secret_id":userid,"secret_key":userkey});
var myHeaders = {"accept": "application/json",
                "Content-Type": "application/json"}

var requestOptions = {
  'method': 'POST',
  'headers': myHeaders,
  'payload': raw
};

var response = UrlFetchApp.fetch("https://ob.nordigen.com/api/v2/token/new/", requestOptions);
var json = response.getContentText();
token = JSON.parse(json).access;

问题原因及解决步骤 #

• URL末尾缺少斜杠导致重定向：Swift代码中使用的URL是https://ob.nordigen.com/api/v2/token/new，而JS代码里的URL带末尾斜杠/。部分API服务器会对不带斜杠的路径返回301重定向，重定向过程中POST请求会被自动转为GET请求，从而触发Method "GET" not allowed的405错误。
  解决：将Swift中的URL改为带末尾斜杠的版本：

  let apiUrl = URL(string: "https://ob.nordigen.com/api/v2/token/new/")!
  

• 请求体参数名错误：对比JS代码可以看到，Nordigen API要求的参数名是secret_id和secret_key，但Swift代码中用了client_id和client_secret，这会导致后续即使解决了405问题，也会返回401认证失败。
  解决：修正请求体的参数名：

  let requestBody: [String: Any] = [
      "secret_id": clientId,
      "secret_key": clientSecret
  ]
  

• 避免强制解包崩溃：代码中使用try!会在JSON序列化失败时直接崩溃，建议用do-catch处理错误：

  do {
      let requestData = try JSONSerialization.data(withJSONObject: requestBody)
      // 后续请求设置代码
  } catch {
      print("JSON序列化失败：\(error)")
  }
  

调整后的完整Swift代码如下：

import Foundation

guard let apiUrl = URL(string: "https://ob.nordigen.com/api/v2/token/new/") else {
    print("无效的API URL")
    exit(1)
}

let secretId = "your_secret_id"
let secretKey = "your_secret_key"
let requestBody: [String: Any] = [
    "secret_id": secretId,
    "secret_key": secretKey
]

do {
    let requestData = try JSONSerialization.data(withJSONObject: requestBody)
    
    var request = URLRequest(url: apiUrl)
    request.httpMethod = "POST"
    request.httpBody = requestData
    request.setValue("application/json", forHTTPHeaderField: "Content-Type")
    request.setValue("application/json", forHTTPHeaderField: "Accept")
    
    let task = URLSession.shared.dataTask(with: request) { (data, response, error) in
        if let error = error {
            print("请求错误：\(error)")
            return
        }
        
        guard let httpResponse = response as? HTTPURLResponse else {
            print("无效的响应")
            return
        }
        
        print("响应状态码：\(httpResponse.statusCode)")
        
        if let data = data, let json = try? JSONSerialization.jsonObject(with: data, options: .fragmentsAllowed) as? [String: Any] {
            print("响应JSON：\(json)")
            if let accessToken = json["access"] as? String {
                print("获取到Access Token: \(accessToken)")
            }
        }
    }
    
    task.resume()
} catch {
    print("JSON序列化失败：\(error)")
}

内容的提问来源于stack exchange，提问作者Pospa