另一个选择是Alamofire库，它提供了可链请求/响应方法。

https://github.com/Alamofire/Alamofire

提出请求

import Alamofire

Alamofire.request(.GET, "http://httpbin.org/get")

响应处理

Alamofire.request(.GET, "http://httpbin.org/get", parameters: ["foo": "bar"])
         .response { request, response, data, error in
              print(request)
              print(response)
              print(error)
          }

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)

 var post:NSString = "api=myposts&userid=\(uid)&page_no=0&limit_no=10"

    NSLog("PostData: %@",post);

    var url1:NSURL = NSURL(string: url)!

    var postData:NSData = post.dataUsingEncoding(NSASCIIStringEncoding)!

    var postLength:NSString = String( postData.length )

    var request:NSMutableURLRequest = NSMutableURLRequest(URL: url1)
    request.HTTPMethod = "POST"
    request.HTTPBody = postData
    request.setValue(postLength, forHTTPHeaderField: "Content-Length")
    request.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
    request.setValue("application/json", forHTTPHeaderField: "Accept")

    var reponseError: NSError?
    var response: NSURLResponse?

    var urlData: NSData? = NSURLConnection.sendSynchronousRequest(request, returningResponse:&response, error:&reponseError)

    if ( urlData != nil ) {
        let res = response as NSHTTPURLResponse!;

        NSLog("Response code: %ld", res.statusCode);

        if (res.statusCode >= 200 && res.statusCode < 300)
        {
            var responseData:NSString  = NSString(data:urlData!, encoding:NSUTF8StringEncoding)!

            NSLog("Response ==> %@", responseData);

            var error: NSError?

            let jsonData:NSDictionary = NSJSONSerialization.JSONObjectWithData(urlData!, options:NSJSONReadingOptions.MutableContainers , error: &error) as NSDictionary

            let success:NSInteger = jsonData.valueForKey("error") as NSInteger

            //[jsonData[@"success"] integerValue];

            NSLog("Success: %ld", success);

            if(success == 0)
            {
                NSLog("Login SUCCESS");

                self.dataArr = jsonData.valueForKey("data") as NSMutableArray
                self.table.reloadData()

            } else {

                NSLog("Login failed1");
                ZAActivityBar.showErrorWithStatus("error", forAction: "Action2")
            }

        } else {

            NSLog("Login failed2");
            ZAActivityBar.showErrorWithStatus("error", forAction: "Action2")

        }
    } else {

        NSLog("Login failed3");
        ZAActivityBar.showErrorWithStatus("error", forAction: "Action2")
}

它一定会对你有帮助

答:吻

URLSession.shared.dataTask(with: URL(string: "https://google.com")!) {(data, response, error) in
    print(String(data: data!, encoding: .utf8))
}.resume()

为了让XCUITest在异步请求完成之前停止测试完成，使用这个(可能会减少100超时):

func test_api() {
    let url = URL(string: "https://jsonplaceholder.typicode.com/posts/42")!
    let exp = expectation(description: "Waiting for data")
    let task = URLSession.shared.dataTask(with: url) {(data, response, error) in
        guard let data = data else { return }
        print(String(data: data, encoding: .utf8)!)
        exp.fulfill()
    }
    task.resume()
    XCTWaiter.wait(for: [exp], timeout: 100)
}

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()