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。
我调用json登录按钮点击
@IBAction func loginClicked(sender : AnyObject) {
var request = NSMutableURLRequest(URL: NSURL(string: kLoginURL)) // Here, kLogin contains the Login API.
var session = NSURLSession.sharedSession()
request.HTTPMethod = "POST"
var err: NSError?
request.HTTPBody = NSJSONSerialization.dataWithJSONObject(self.criteriaDic(), options: nil, error: &err) // This Line fills the web service with required parameters.
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
request.addValue("application/json", forHTTPHeaderField: "Accept")
var task = session.dataTaskWithRequest(request, completionHandler: {data, response, error -> Void in
var strData = NSString(data: data, encoding: NSUTF8StringEncoding)
var err1: NSError?
var json2 = NSJSONSerialization.JSONObjectWithData(strData.dataUsingEncoding(NSUTF8StringEncoding), options: .MutableLeaves, error:&err1 ) as NSDictionary
println("json2 :\(json2)")
if(err) {
println(err!.localizedDescription)
}
else {
var success = json2["success"] as? Int
println("Success: \(success)")
}
})
task.resume()
}
在这里，我为参数创建了一个单独的字典。
var params = ["format":"json", "MobileType":"IOS","MIN":"f8d16d98ad12acdbbe1de647414495ec","UserName":emailTxtField.text,"PWD":passwordTxtField.text,"SigninVia":"SH"]as NSDictionary
return params
}
// You can add your own sets of parameter here.
检查以下代码:
1. SynchonousRequest
斯威夫特1.2
let urlPath: String = "YOUR_URL_HERE"
var url: NSURL = NSURL(string: urlPath)!
var request1: NSURLRequest = NSURLRequest(URL: url)
var response: AutoreleasingUnsafeMutablePointer<NSURLResponse?>=nil
var dataVal: NSData = NSURLConnection.sendSynchronousRequest(request1, returningResponse: response, error:nil)!
var err: NSError
println(response)
var jsonResult: NSDictionary = NSJSONSerialization.JSONObjectWithData(dataVal, options: NSJSONReadingOptions.MutableContainers, error: &err) as? NSDictionary
println("Synchronous\(jsonResult)")
快速2.0 +
let urlPath: String = "YOUR_URL_HERE"
let url: NSURL = NSURL(string: urlPath)!
let request1: NSURLRequest = NSURLRequest(URL: url)
let response: AutoreleasingUnsafeMutablePointer<NSURLResponse?>=nil
do{
let dataVal = try NSURLConnection.sendSynchronousRequest(request1, returningResponse: response)
print(response)
do {
if let jsonResult = try NSJSONSerialization.JSONObjectWithData(dataVal, options: []) as? NSDictionary {
print("Synchronous\(jsonResult)")
}
} catch let error as NSError {
print(error.localizedDescription)
}
}catch let error as NSError
{
print(error.localizedDescription)
}
2. AsynchonousRequest
斯威夫特1.2
let urlPath: String = "YOUR_URL_HERE"
var url: NSURL = NSURL(string: urlPath)!
var request1: NSURLRequest = NSURLRequest(URL: url)
let queue:NSOperationQueue = NSOperationQueue()
NSURLConnection.sendAsynchronousRequest(request1, queue: queue, completionHandler:{ (response: NSURLResponse!, data: NSData!, error: NSError!) -> Void in
var err: NSError
var jsonResult: NSDictionary = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: nil) as NSDictionary
println("Asynchronous\(jsonResult)")
})
快速2.0 +
let urlPath: String = "YOUR_URL_HERE"
let url: NSURL = NSURL(string: urlPath)!
let request1: NSURLRequest = NSURLRequest(URL: url)
let queue:NSOperationQueue = NSOperationQueue()
NSURLConnection.sendAsynchronousRequest(request1, queue: queue, completionHandler:{ (response: NSURLResponse?, data: NSData?, error: NSError?) -> Void in
do {
if let jsonResult = try NSJSONSerialization.JSONObjectWithData(data!, options: []) as? NSDictionary {
print("ASynchronous\(jsonResult)")
}
} catch let error as NSError {
print(error.localizedDescription)
}
})
3.和往常一样，URL连接
斯威夫特1.2
var dataVal = NSMutableData()
let urlPath: String = "YOUR URL HERE"
var url: NSURL = NSURL(string: urlPath)!
var request: NSURLRequest = NSURLRequest(URL: url)
var connection: NSURLConnection = NSURLConnection(request: request, delegate: self, startImmediately: true)!
connection.start()
Then
func connection(connection: NSURLConnection!, didReceiveData data: NSData!){
self.dataVal?.appendData(data)
}
func connectionDidFinishLoading(connection: NSURLConnection!)
{
var error: NSErrorPointer=nil
var jsonResult: NSDictionary = NSJSONSerialization.JSONObjectWithData(dataVal!, options: NSJSONReadingOptions.MutableContainers, error: error) as NSDictionary
println(jsonResult)
}
快速2.0 +
var dataVal = NSMutableData()
let urlPath: String = "YOUR URL HERE"
var url: NSURL = NSURL(string: urlPath)!
var request: NSURLRequest = NSURLRequest(URL: url)
var connection: NSURLConnection = NSURLConnection(request: request, delegate: self, startImmediately: true)!
connection.start()
Then
func connection(connection: NSURLConnection!, didReceiveData data: NSData!){
dataVal.appendData(data)
}
func connectionDidFinishLoading(connection: NSURLConnection!)
{
do {
if let jsonResult = try NSJSONSerialization.JSONObjectWithData(dataVal, options: []) as? NSDictionary {
print(jsonResult)
}
} catch let error as NSError {
print(error.localizedDescription)
}
}
4. 异步POST请求
斯威夫特1.2
let urlPath: String = "YOUR URL HERE"
var url: NSURL = NSURL(string: urlPath)!
var request1: NSMutableURLRequest = NSMutableURLRequest(URL: url)
request1.HTTPMethod = "POST"
var stringPost="deviceToken=123456" // Key and Value
let data = stringPost.dataUsingEncoding(NSUTF8StringEncoding)
request1.timeoutInterval = 60
request1.HTTPBody=data
request1.HTTPShouldHandleCookies=false
let queue:NSOperationQueue = NSOperationQueue()
NSURLConnection.sendAsynchronousRequest(request1, queue: queue, completionHandler:{ (response: NSURLResponse!, data: NSData!, error: NSError!) -> Void in
var err: NSError
var jsonResult: NSDictionary = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: nil) as NSDictionary
println("AsSynchronous\(jsonResult)")
})
快速2.0 +
let urlPath: String = "YOUR URL HERE"
let url: NSURL = NSURL(string: urlPath)!
let request1: NSMutableURLRequest = NSMutableURLRequest(URL: url)
request1.HTTPMethod = "POST"
let stringPost="deviceToken=123456" // Key and Value
let data = stringPost.dataUsingEncoding(NSUTF8StringEncoding)
request1.timeoutInterval = 60
request1.HTTPBody=data
request1.HTTPShouldHandleCookies=false
let queue:NSOperationQueue = NSOperationQueue()
NSURLConnection.sendAsynchronousRequest(request1, queue: queue, completionHandler:{ (response: NSURLResponse?, data: NSData?, error: NSError?) -> Void in
do {
if let jsonResult = try NSJSONSerialization.JSONObjectWithData(data!, options: []) as? NSDictionary {
print("ASynchronous\(jsonResult)")
}
} catch let error as NSError {
print(error.localizedDescription)
}
})
5. 异步GET请求
斯威夫特1.2
let urlPath: String = "YOUR URL HERE"
var url: NSURL = NSURL(string: urlPath)!
var request1: NSMutableURLRequest = NSMutableURLRequest(URL: url)
request1.HTTPMethod = "GET"
request1.timeoutInterval = 60
let queue:NSOperationQueue = NSOperationQueue()
NSURLConnection.sendAsynchronousRequest(request1, queue: queue, completionHandler:{ (response: NSURLResponse!, data: NSData!, error: NSError!) -> Void in
var err: NSError
var jsonResult: NSDictionary = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: nil) as NSDictionary
println("AsSynchronous\(jsonResult)")
})
快速2.0 +
let urlPath: String = "YOUR URL HERE"
let url: NSURL = NSURL(string: urlPath)!
let request1: NSMutableURLRequest = NSMutableURLRequest(URL: url)
request1.HTTPMethod = "GET"
let queue:NSOperationQueue = NSOperationQueue()
NSURLConnection.sendAsynchronousRequest(request1, queue: queue, completionHandler:{ (response: NSURLResponse?, data: NSData?, error: NSError?) -> Void in
do {
if let jsonResult = try NSJSONSerialization.JSONObjectWithData(data!, options: []) as? NSDictionary {
print("ASynchronous\(jsonResult)")
}
} catch let error as NSError {
print(error.localizedDescription)
}
})
6. 上传图片(文件)
快速2.0 +
let mainURL = "YOUR_URL_HERE"
let url = NSURL(string: mainURL)
let request = NSMutableURLRequest(URL: url!)
let boundary = "78876565564454554547676"
request.addValue("multipart/form-data; boundary=\(boundary)", forHTTPHeaderField: "Content-Type")
request.HTTPMethod = "POST" // POST OR PUT What you want
let session = NSURLSession(configuration:NSURLSessionConfiguration.defaultSessionConfiguration(), delegate: nil, delegateQueue: nil)
let imageData = UIImageJPEGRepresentation(UIImage(named: "Test.jpeg")!, 1)
var body = NSMutableData()
body.appendData("--\(boundary)\r\n".dataUsingEncoding(NSUTF8StringEncoding)!)
// Append your parameters
body.appendData("Content-Disposition: form-data; name=\"name\"\r\n\r\n".dataUsingEncoding(NSUTF8StringEncoding)!)
body.appendData("PREMKUMAR\r\n".dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: true)!)
body.appendData("--\(boundary)\r\n".dataUsingEncoding(NSUTF8StringEncoding)!)
body.appendData("Content-Disposition: form-data; name=\"description\"\r\n\r\n".dataUsingEncoding(NSUTF8StringEncoding)!)
body.appendData("IOS_DEVELOPER\r\n".dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: true)!)
body.appendData("--\(boundary)\r\n".dataUsingEncoding(NSUTF8StringEncoding)!)
// Append your Image/File Data
var imageNameval = "HELLO.jpg"
body.appendData("--\(boundary)\r\n".dataUsingEncoding(NSUTF8StringEncoding)!)
body.appendData("Content-Disposition: form-data; name=\"profile_photo\"; filename=\"\(imageNameval)\"\r\n".dataUsingEncoding(NSUTF8StringEncoding)!)
body.appendData("Content-Type: image/jpeg\r\n\r\n".dataUsingEncoding(NSUTF8StringEncoding)!)
body.appendData(imageData!)
body.appendData("\r\n".dataUsingEncoding(NSUTF8StringEncoding)!)
body.appendData("--\(boundary)--\r\n".dataUsingEncoding(NSUTF8StringEncoding)!)
request.HTTPBody = body
let dataTask = session.dataTaskWithRequest(request) { (data, response, error) -> Void in
if error != nil {
//handle error
}
else {
let outputString : NSString = NSString(data:data!, encoding:NSUTF8StringEncoding)!
print("Response:\(outputString)")
}
}
dataTask.resume()
更新:Xcode 13.0和Swift 5+
获取HTTP请求
let url = URL(string: "URL HERE")! //PUT Your URL
var request = URLRequest(url: url)
request.httpMethod = "GET"
let task = URLSession.shared.dataTask(with: request) { data, response, error in
guard let safeData = data,
let response = response as? HTTPURLResponse,
error == nil else { // check for fundamental networking error
print("error", error ?? "Unknown error")
delegate?.onError(error!)
return
}
guard (200 ... 299) ~= response.statusCode else { // check for http errors
print("statusCode should be 2xx, but is \(response.statusCode)")
print("response = \(response)")
return
}
let responseString = String(data: safeData, encoding: .utf8)
print("Response String = \(responseString)")
}
task.resume()
一个简单的Swift 2.0方法来发出HTTP GET请求
HTTP请求是异步的，因此需要一种方法从HTTP请求中获取返回值。这种方法使用通知器，分布在两个类中。
示例是使用网站http://www.example.com/handler.php?do=CheckUserJson&json=检查标识符令牌的用户名和密码，该文件名为handler.php，并且在do参数上有一个switch语句以获得RESTful方法。
在viewDidLoad中，我们设置了NotifierObserver，设置了json，并调用getHTTPRequest函数。它将返回函数checkedUsernameAndPassword和从http请求返回的参数。
override func viewDidLoad() {
super.viewDidLoad()
// setup the Notification observer to catch the result of check username and password
NSNotificationCenter.defaultCenter().addObserver(self, selector: "checkedUsernameAndPassword:", name: CHECK_USERNAME_AND_PASSWORD, object: nil)
let username = GlobalVariables.USER_NAME
let password = GlobalVariables.PASSWORD
// check username and password
if let jsonString = Utility.checkUsernameAndPasswordJson(username, password:password){
print("json string returned = \(jsonString)")
let url = CHECKUSERJSON+jsonString
// CHECKUSERJSON = http://www.example.com/handler.php?do=CheckUserJson&json=
// jsonString = {\"username\":\"demo\",\"password\":\"demo\"}"
// the php script handles a json request and returns a string identifier
Utility.getHTTPRequest(url,notifierId: CHECK_USERNAME_AND_PASSWORD)
// the returned identifier is sent to the checkedUsernaeAndPassword function when it becomes availabel.
}
}
在Utility.swift中有两个静态函数，首先用于编码json，然后执行HTTP调用。
static func checkUsernameAndPasswordJson(username: String, password: String) -> String?{
let para:NSMutableDictionary = NSMutableDictionary()
para.setValue("demo", forKey: "username")
para.setValue("demo", forKey: "password")
let jsonData: NSData
do{
jsonData = try NSJSONSerialization.dataWithJSONObject(para, options: NSJSONWritingOptions())
let jsonString = NSString(data: jsonData, encoding: NSUTF8StringEncoding) as! String
return jsonString
} catch _ {
print ("UH OOO")
return nil
}
}
和Http请求
static func getHTTPRequest (url:String , notifierId: String) -> Void{
let urlString = url
let config = NSURLSessionConfiguration.defaultSessionConfiguration()
let session = NSURLSession(configuration: config, delegate: nil, delegateQueue: nil)
let safeURL = urlString.stringByAddingPercentEncodingWithAllowedCharacters(NSCharacterSet.URLQueryAllowedCharacterSet())!
if let url = NSURL(string: safeURL){
let request = NSMutableURLRequest(URL: url)
request.HTTPMethod = "GET"
request.timeoutInterval = 60
let taskData = session.dataTaskWithRequest(request, completionHandler: {
(data:NSData?, response:NSURLResponse?, error:NSError?) -> Void in
if (data != nil) {
let result = NSString(data: data! , encoding: NSUTF8StringEncoding)
sendNotification (notifierId, message: String(result), num: 0)
}else{
sendNotification (notifierId, message: String(UTF8String: nil), num: -1) }
})
taskData.resume()
}else{
print("bad urlString = \(urlString)")
}
}
sendNotification函数完成了循环。注意，在观察者中，在选择器字符串的末尾有一个“:”。这允许通知在userInfo中携带有效负载。我给它一个String和Int。
static func sendNotification (key: String, message:String?, num: Int?){
NSNotificationCenter.defaultCenter().postNotificationName(
key,
object: nil,
userInfo: (["message": message!,
"num": "\(num!)"])
)
}
注意，使用HTTP是老式的，更喜欢HTTPS见我如何加载一个HTTP URL与应用程序传输安全启用在iOS 9?
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