我在iBooks上读了苹果的编程语言Swift，但不知道如何在Swift中发出HTTP请求(类似cURL)。我需要导入Obj-C类还是只需要导入默认库?或者不能基于原生Swift代码进行HTTP请求?
当前回答
Swift 4及以上:使用URLSession API进行数据请求
// create the url
let url = URL(string: "https://jsonplaceholder.typicode.com/todos/1")! //change the url
// create the session object
let session = URLSession.shared
// now create the URLRequest object using the url object
let request = URLRequest(url: url)
// create dataTask using the session object to send data to the server
let task = session.dataTask(with: request as URLRequest, completionHandler: { data, response, error in
guard error == nil else {
return
}
guard let data = data else {
return
}
do {
//create json object from data
if let json = try JSONSerialization.jsonObject(with: data, options: .mutableContainers) as? [String: Any] {
print(json)
}
} catch let error {
print(error.localizedDescription)
}
})
task.resume()
Swift 4及以上，可解码和结果enum
// APIError enum which shows all possible Network errors
enum APIError: Error {
case networkError(Error)
case dataNotFound
case jsonParsingError(Error)
case invalidStatusCode(Int)
case badURL(String)
}
// Result enum to show success or failure
enum Result<T> {
case success(T)
case failure(AppError)
}
// dataRequest which sends request to given URL and convert to Decodable Object
func dataRequest<T: Decodable>(with url: String, objectType: T.Type, completion: @escaping (Result<T>) -> Void) {
// create the url with NSURL
guard let dataURL = URL(string: url) else {
completion(.failure(APIError.badURL(url))
return
}
// create the session object
let session = URLSession.shared
// now create the URLRequest object using the url object
let request = URLRequest(url: dataURL, cachePolicy: .useProtocolCachePolicy, timeoutInterval: 60)
// create dataTask using the session object to send data to the server
let task = session.dataTask(with: request, completionHandler: { data, response, error in
guard error == nil else {
completion(Result.failure(APIError.networkError(error!)))
return
}
guard let data = data else {
completion(Result.failure(AppError.dataNotFound))
return
}
do {
// create decodable object from data
let decodedObject = try JSONDecoder().decode(objectType.self, from: data)
completion(Result.success(decodedObject))
} catch let error {
completion(Result.failure(APIError.jsonParsingError(error as! DecodingError)))
}
})
task.resume()
}
例子:
//如果我们想从占位符API获取todo，那么我们定义todo结构体并调用dataRequest并传递“https://jsonplaceholder.typicode.com/todos/1”字符串url。
struct ToDo: Decodable {
let id: Int
let userId: Int
let title: String
let completed: Bool
}
dataRequest(with: "https://jsonplaceholder.typicode.com/todos/1", objectType: ToDo.self) { (result: Result) in
switch result {
case .success(let object):
print(object)
case .failure(let error):
print(error)
}
}
//输出结果:
ToDo(id: 1, userId: 1, title: "delectus aut autem", completed: false)
其他回答
你可以使用Just，一个python-requests风格的HTTP库。
使用Just发送HTTP请求的示例:
// synchronous GET request with URL query a=1
let r = Just.get("https://httpbin.org/get", params:["a":1])
// asynchronous POST request with form value and file uploads
Just.post(
"http://justiceleauge.org/member/register",
data: ["username": "barryallen", "password":"ReverseF1ashSucks"],
files: ["profile_photo": .URL(fileURLWithPath:"flash.jpeg", nil)]
) { (r)
if (r.ok) { /* success! */ }
}
在这两种情况下，可以通过类似于python-request的方式访问请求r的结果:
r.ok // is the response successful?
r.statusCode // status code of response
r.content // response body as NSData?
r.text // response body as text?
r.json // response body parsed by NSJSONSerielization
你可以在这个操场上找到更多的例子
在操场上以同步模式使用这个库是Swift中最接近cURL的东西。
Swift 4及以上:使用URLSession API进行数据请求
// create the url
let url = URL(string: "https://jsonplaceholder.typicode.com/todos/1")! //change the url
// create the session object
let session = URLSession.shared
// now create the URLRequest object using the url object
let request = URLRequest(url: url)
// create dataTask using the session object to send data to the server
let task = session.dataTask(with: request as URLRequest, completionHandler: { data, response, error in
guard error == nil else {
return
}
guard let data = data else {
return
}
do {
//create json object from data
if let json = try JSONSerialization.jsonObject(with: data, options: .mutableContainers) as? [String: Any] {
print(json)
}
} catch let error {
print(error.localizedDescription)
}
})
task.resume()
Swift 4及以上，可解码和结果enum
// APIError enum which shows all possible Network errors
enum APIError: Error {
case networkError(Error)
case dataNotFound
case jsonParsingError(Error)
case invalidStatusCode(Int)
case badURL(String)
}
// Result enum to show success or failure
enum Result<T> {
case success(T)
case failure(AppError)
}
// dataRequest which sends request to given URL and convert to Decodable Object
func dataRequest<T: Decodable>(with url: String, objectType: T.Type, completion: @escaping (Result<T>) -> Void) {
// create the url with NSURL
guard let dataURL = URL(string: url) else {
completion(.failure(APIError.badURL(url))
return
}
// create the session object
let session = URLSession.shared
// now create the URLRequest object using the url object
let request = URLRequest(url: dataURL, cachePolicy: .useProtocolCachePolicy, timeoutInterval: 60)
// create dataTask using the session object to send data to the server
let task = session.dataTask(with: request, completionHandler: { data, response, error in
guard error == nil else {
completion(Result.failure(APIError.networkError(error!)))
return
}
guard let data = data else {
completion(Result.failure(AppError.dataNotFound))
return
}
do {
// create decodable object from data
let decodedObject = try JSONDecoder().decode(objectType.self, from: data)
completion(Result.success(decodedObject))
} catch let error {
completion(Result.failure(APIError.jsonParsingError(error as! DecodingError)))
}
})
task.resume()
}
例子:
//如果我们想从占位符API获取todo，那么我们定义todo结构体并调用dataRequest并传递“https://jsonplaceholder.typicode.com/todos/1”字符串url。
struct ToDo: Decodable {
let id: Int
let userId: Int
let title: String
let completed: Bool
}
dataRequest(with: "https://jsonplaceholder.typicode.com/todos/1", objectType: ToDo.self) { (result: Result) in
switch result {
case .success(let object):
print(object)
case .failure(let error):
print(error)
}
}
//输出结果:
ToDo(id: 1, userId: 1, title: "delectus aut autem", completed: false)
你可以使用URL URLRequest URLSession或者NSURLConnection就像你在Objective-C中通常做的那样。注意，对于iOS 7.0及更高版本，URLSession是首选。
使用URLSession
初始化URL对象和URLSession中的URLSessionDataTask。然后使用resume()运行任务。
let url = URL(string: "http://www.stackoverflow.com")!
let task = URLSession.shared.dataTask(with: url) {(data, response, error) in
guard let data = data else { return }
print(String(data: data, encoding: .utf8)!)
}
task.resume()
使用NSURLConnection
首先，初始化URL和URLRequest:
let url = URL(string: "http://www.stackoverflow.com")!
var request = URLRequest(url: url)
request.httpMethod = "POST"
然后，你可以异步加载请求:
NSURLConnection.sendAsynchronousRequest(request, queue: OperationQueue.main) {(response, data, error) in
guard let data = data else { return }
print(String(data: data, encoding: .utf8)!)
}
或者你可以初始化一个NSURLConnection:
let connection = NSURLConnection(request: request, delegate:nil, startImmediately: true)
只是要确保将委托设置为nil以外的东西，并使用委托方法处理接收到的响应和数据。
要了解更多细节，请查看NSURLConnectionDataDelegate协议的文档
在Xcode操场上测试
如果你想在Xcode游乐场上尝试这段代码，添加import PlaygroundSupport到你的游乐场，以及下面的调用:
PlaygroundPage.current.needsIndefiniteExecution = true
这将允许你在操场上使用异步代码。
使用URLSession + Swift
只是补充cezar的答案，如果你想使用苹果的URLSession类进行web请求，有多种方法来完成任务
简单的GET请求与URL 简单的GET请求与URL和参数 简单的GET请求与错误处理的URL 简单的POST请求与URL，参数与错误处理
1. 简单的GET请求与URL
func simpleGetUrlRequest()
{
let url = URL(string: "https://httpbin.org/get")!
let task = URLSession.shared.dataTask(with: url) {(data, response, error) in
guard let data = data else { return }
print("The response is : ",String(data: data, encoding: .utf8)!)
//print(NSString(data: data, encoding: String.Encoding.utf8.rawValue) as Any)
}
task.resume()
}
注意:请确保您必须在pList中为http请求添加“NSAppTransportSecurity”键
<key>NSAppTransportSecurity</key>
<dict>
<key>NSAllowsArbitraryLoads</key>
<true/>
</dict>
2. 简单的GET请求与URL和参数
func simpleGetUrlWithParamRequest()
{
let url = URL(string: "https://www.google.com/search?q=peace")!
let task = URLSession.shared.dataTask(with: url) {(data, response, error) in
if error != nil || data == nil {
print("Client error!")
return
}
guard let response = response as? HTTPURLResponse, (200...299).contains(response.statusCode) else {
print("Server error!")
return
}
print("The Response is : ",response)
}
task.resume()
}
3.简单的GET请求与错误处理的URL
func simpleGetUrlRequestWithErrorHandling()
{
let session = URLSession.shared
let url = URL(string: "https://httpbin.org/get")!
let task = session.dataTask(with: url) { data, response, error in
if error != nil || data == nil {
print("Client error!")
return
}
guard let response = response as? HTTPURLResponse, (200...299).contains(response.statusCode) else {
print("Server error!")
return
}
guard let mime = response.mimeType, mime == "application/json" else {
print("Wrong MIME type!")
return
}
do {
let json = try JSONSerialization.jsonObject(with: data!, options: [])
print("The Response is : ",json)
} catch {
print("JSON error: \(error.localizedDescription)")
}
}
task.resume()
}
4. 简单的POST请求与URL，参数与错误处理。
func simplePostRequestWithParamsAndErrorHandling(){
let configuration = URLSessionConfiguration.default
configuration.timeoutIntervalForRequest = 30
configuration.timeoutIntervalForResource = 30
let session = URLSession(configuration: configuration)
let url = URL(string: "https://httpbin.org/post")!
var request = URLRequest(url: url)
request.httpMethod = "POST"
request.setValue("application/json", forHTTPHeaderField: "Content-Type")
request.addValue("application/json", forHTTPHeaderField: "Accept")
let parameters = ["username": "foo", "password": "123456"]
do {
request.httpBody = try JSONSerialization.data(withJSONObject: parameters, options: .prettyPrinted)
} catch let error {
print(error.localizedDescription)
}
let task = session.dataTask(with: request as URLRequest, completionHandler: { data, response, error in
if error != nil || data == nil {
print("Client error!")
return
}
guard let response = response as? HTTPURLResponse, (200...299).contains(response.statusCode) else {
print("Oops!! there is server error!")
return
}
guard let mime = response.mimeType, mime == "application/json" else {
print("response is not json")
return
}
do {
let json = try JSONSerialization.jsonObject(with: data!, options: [])
print("The Response is : ",json)
} catch {
print("JSON error: \(error.localizedDescription)")
}
})
task.resume()
}
谢谢你的建议!!
在Swift 4.1和Xcode 9.4.1中。
JSON POST方法示例。要检查互联网连接，从https://developer.apple.com/library/archive/samplecode/Reachability/Introduction/Intro.html#//apple_ref/doc/uid/DTS40007324-Intro-DontLinkElementID_2添加Reachability.h & .m文件
func yourFunctionName {
//Check internet connection
let networkReachability = Reachability.forInternetConnection()
let networkStatus:Int = (networkReachability?.currentReachabilityStatus())!.rawValue
print(networkStatus)
if networkStatus == NotReachable.rawValue {
let msg = SharedClass.sharedInstance.noNetMsg//Message
//Call alert from shared class
SharedClass.sharedInstance.alert(view: self, title: "", message: msg)
} else {
//Call spinner from shared class
SharedClass.sharedInstance.activityIndicator(view: self.view)//Play spinner
let parameters = "Your parameters here"
var request = URLRequest(url: URL(string: url)!)
request.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
request.httpMethod = "POST"
print("URL : \(request)")
request.httpBody = parameters.data(using: .utf8)
let task = URLSession.shared.dataTask(with: request) { data, response, error in guard let data = data, error == nil else { // check for fundamental networking error
//Stop spinner
SharedClass.sharedInstance.stopActivityIndicator() //Stop spinner
//Print error in alert
SharedClass.sharedInstance.alert(view: self, title: "", message: "\(String(describing: error!.localizedDescription))")
return
}
SharedClass.sharedInstance.stopActivityIndicator() //Stop spinner
if let httpStatus = response as? HTTPURLResponse, httpStatus.statusCode != 200 { // check for http errors
print("statusCode should be 200, but is \(httpStatus.statusCode)")
print("response = \(String(describing: response))")
}
do {
let response = try JSONSerialization.jsonObject(with: data, options: []) as? [String: AnyObject]
print(response!)
//Your code here
} catch let error as NSError {
print(error)
}
}
task.resume()
}
}
如果你有兴趣在SharedClass中使用这个函数
//My shared class
import UIKit
class SharedClass: NSObject {
static let sharedInstance = SharedClass()
func postRequestFunction(apiName: String , parameters: String, onCompletion: @escaping (_ success: Bool, _ error: Error?, _ result: [String: Any]?)->()) {
var URL = "your URL here/index.php/***?"
URL = URL.replacingOccurrences(of: "***", with: apiName)
var request = URLRequest(url: URL(string: URL)!)
request.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
request.httpMethod = "POST"
print("shared URL : \(request)")
request.httpBody = parameters.data(using: .utf8)
var returnRes:[String:Any] = [:]
let task = URLSession.shared.dataTask(with: request) { data, response, error in
if let error = error {
onCompletion(false, error, nil)
} else {
guard let data = data else {
onCompletion(false, error, nil)
return
}
if let httpStatus = response as? HTTPURLResponse, httpStatus.statusCode == 200 {
do {
returnRes = try JSONSerialization.jsonObject(with: data, options: []) as! [String : Any]
onCompletion(true, nil, returnRes)
} catch let error as NSError {
onCompletion(false, error, nil)
}
} else {
onCompletion(false, error, nil)
}
}
}
task.resume()
}
private override init() {
}
最后像这样调用这个函数....
SharedClass.sharedInstance.postRequestFunction(apiName: "Your API name", parameters: parameters) { (success, error, result) in
print(result!)
if success {
//Your code here
} else {
print(error?.localizedDescription ?? "")
}
}
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