至少在10.3版本之前，URLRequest中缺少POST数据的iOS

let url = URL(string: "https://example.com/api")
var request = URLRequest(url: url!)
request.httpMethod = "POST"
let postData = "key1=value1&key2=value2"
request.httpBody = postData.data(using: .utf8)

// 发送请求
let task = URLSession.shared.dataTask(with: request) { (data, response, error) in
    if let error = error {
        print("请求失败：\(error)")
    } else if let data = data {
        let responseString = String(data: data, encoding: .utf8)
        print("请求成功：\(responseString ?? "")")
    }
}
task.resume()

var components = URLComponents(string: "https://example.com/api")
let queryItems = [
    URLQueryItem(name: "key1", value: "value1"),
    URLQueryItem(name: "key2", value: "value2")
]
components?.queryItems = queryItems

let url = components?.url
var request = URLRequest(url: url!)
request.httpMethod = "POST"

// 发送请求
let task = URLSession.shared.dataTask(with: request) { (data, response, error) in
    if let error = error {
        print("请求失败：\(error)")
    } else if let data = data {
        let responseString = String(data: data, encoding: .utf8)
        print("请求成功：\(responseString ?? "")")
    }
}
task.resume()