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

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。

其他回答

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)

下面是一个非常简单的Swift 4在操场上的例子:

import UIKit
// run asynchronously in a playground
import PlaygroundSupport
PlaygroundPage.current.needsIndefiniteExecution = true

// create a url
let url = URL(string: "http://www.stackoverflow.com")

// create a data task
let task = URLSession.shared.dataTask(with: url!) { (data, response, error) in
    if error != nil {
        print("there's a problem")
    }
    print(String(data: data!, encoding: String.Encoding.utf8) ?? "")
}

//running the task w/ resume
task.resume()

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.

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。

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()