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!!

我已经完成了HTTP请求两种方法GET和POST与JSON解析的方式:

在viewDidLoad ():

override func viewDidLoad() {
super.viewDidLoad()

    makeGetRequest()
    makePostRequest()

}

func makePostRequest(){

    let urlPath: String = "http://www.swiftdeveloperblog.com/http-post-example-script/"
    var url: NSURL = NSURL(string: urlPath)!
    var request: NSMutableURLRequest = NSMutableURLRequest(URL: url)

    request.HTTPMethod = "POST"
    var stringPost="firstName=James&lastName=Bond" // Key and Value

    let data = stringPost.dataUsingEncoding(NSUTF8StringEncoding)

    request.timeoutInterval = 60
    request.HTTPBody=data
    request.HTTPShouldHandleCookies=false

    let queue:NSOperationQueue = NSOperationQueue()

    NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue(), completionHandler:{ (response:NSURLResponse!, data: NSData!, error: NSError!) -> Void in
        var error: AutoreleasingUnsafeMutablePointer<NSError?> = nil
        let jsonResult: NSDictionary! = NSJSONSerialization.JSONObjectWithData(data, options:NSJSONReadingOptions.MutableContainers, error: error) as? NSDictionary

         if (jsonResult != nil) {
            // Success
           println(jsonResult)

           let message = jsonResult["Message"] as! NSString

           println(message)
         }else {
            // Failed
            println("Failed")
        }

    })

}

func makeGetRequest(){
    var url : String = "http://api.androidhive.info/contacts/"
    var request : NSMutableURLRequest = NSMutableURLRequest()
    request.URL = NSURL(string: url)
    request.HTTPMethod = "GET"
    request.timeoutInterval = 60

    NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue(), completionHandler:{ (response:NSURLResponse!, data: NSData!, error: NSError!) -> Void in
        var error: AutoreleasingUnsafeMutablePointer<NSError?> = nil
        let jsonResult: NSDictionary! = NSJSONSerialization.JSONObjectWithData(data, options:NSJSONReadingOptions.MutableContainers, error: error) as? NSDictionary

        if (jsonResult != nil) {
            // Success
            println(jsonResult)

            let dataArray = jsonResult["contacts"] as! NSArray;

            for item in dataArray { // loop through data items

                let obj = item as! NSDictionary

                for (key, value) in obj {

                    println("Key: \(key) - Value: \(value)")

                    let phone = obj["phone"] as! NSDictionary;

                    let mobile = phone["mobile"] as! NSString
                    println(mobile)
                    let home = phone["home"] as! NSString
                    println(home)
                    let office = phone["office"] as! NSString
                    println(office)
                }
            }

        } else {
            // Failed
            println("Failed")
        }

    })
}

Done

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)

下面是在Linux上使用Swift进行HTTP请求的从头到尾的说明。

首先创建一个SwiftPM包

mkdir swift-http && cd swift-http && swift package init --type executable

然后替换。/Sources/swift-http/main.swift 代码如下:

import Foundation
import FoundationNetworking

let sema = DispatchSemaphore(value: 0)

URLSession.shared.dataTask(with: URL(string: "http://numbersapi.com/42")!) {(data, response, error) in
    print(String(data: data!, encoding: .utf8) ?? String(describing: error))
    sema.signal()
}.resume()

sema.wait()

然后运行代码

swift run

输出的例子:

[6/6] Build complete!
42 is the answer to the Ultimate Question of Life, the Universe, and Everything.

注意:使用DispatchSemaphore是为了使程序在得到响应之前不会退出。

你也可以这样做:

import Foundation
import FoundationNetworking

var done = false

URLSession.shared.dataTask(with: URL(string: "http://numbersapi.com/42")!) {(data, response, error) in
    print(String(data: data!, encoding: .utf8) ?? String(describing: error))
    done = true
}.resume()

while !done { Thread.sleep(forTimeInterval: 1) }

斯威夫特3.0

通过一个小抽象 https://github.com/daltoniam/swiftHTTP

例子

    do {
        let opt = try HTTP.GET("https://google.com")
        opt.start { response in
            if let err = response.error {
                print("error: \(err.localizedDescription)")
                return //also notify app of failure as needed
            }
            print("opt finished: \(response.description)")
            //print("data is: \(response.data)") access the response of the data with response.data
        }
    } catch let error {
        print("got an error creating the request: \(error)")
    }

细节

Xcode 9.2, Swift 4 Xcode 10.2.1 (10E1001)

Info.plist

NSApp传输安全

添加到info plist:

<key>NSAppTransportSecurity</key>
<dict>
    <key>NSAllowsArbitraryLoads</key>
    <true/>
</dict>

Alamofire样本

Alamofire

import Alamofire

class AlamofireDataManager {
    fileprivate let queue: DispatchQueue
    init(queue: DispatchQueue) { self.queue = queue }

    private func createError(message: String, code: Int) -> Error {
        return NSError(domain: "dataManager", code: code, userInfo: ["message": message ])
    }

    private func make(session: URLSession = URLSession.shared, request: URLRequest, closure: ((Result<[String: Any]>) -> Void)?) {
        Alamofire.request(request).responseJSON { response in
            let complete: (Result<[String: Any]>) ->() = { result in DispatchQueue.main.async { closure?(result) } }
            switch response.result {
                case .success(let value): complete(.success(value as! [String: Any]))
                case .failure(let error): complete(.failure(error))
            }
        }
    }

    func searchRequest(term: String, closure: ((Result<[String: Any]>) -> Void)?) {
        guard let url = URL(string: "https://itunes.apple.com/search?term=\(term.replacingOccurrences(of: " ", with: "+"))") else { return }
        let request = URLRequest(url: url)
        make(request: request) { response in closure?(response) }
    }
}

Alamofire样品的使用

private lazy var alamofireDataManager = AlamofireDataManager(queue: DispatchQueue(label: "DataManager.queue", qos: .utility))
//.........

alamofireDataManager.searchRequest(term: "jack johnson") { result in
      print(result.value ?? "no data")
      print(result.error ?? "no error")
}

URLSession样本

import Foundation

class DataManager {

    fileprivate let queue: DispatchQueue
        init(queue: DispatchQueue) { self.queue = queue }

    private func createError(message: String, code: Int) -> Error {
        return NSError(domain: "dataManager", code: code, userInfo: ["message": message ])
    }

    private func make(session: URLSession = URLSession.shared, request: URLRequest, closure: ((_ json: [String: Any]?, _ error: Error?)->Void)?) {
        let task = session.dataTask(with: request) { [weak self] data, response, error in
            self?.queue.async {
                let complete: (_ json: [String: Any]?, _ error: Error?) ->() = { json, error in DispatchQueue.main.async { closure?(json, error) } }

                guard let self = self, error == nil else { complete(nil, error); return }
                guard let data = data else { complete(nil, self.createError(message: "No data", code: 999)); return }

                do {
                    if let json = try JSONSerialization.jsonObject(with: data, options: .mutableContainers) as? [String: Any] {
                        complete(json, nil)
                    }
                } catch let error { complete(nil, error); return }
            }
        }

        task.resume()
    }

    func searchRequest(term: String, closure: ((_ json: [String: Any]?, _ error: Error?)->Void)?) {
        let url = URL(string: "https://itunes.apple.com/search?term=\(term.replacingOccurrences(of: " ", with: "+"))")
        let request = URLRequest(url: url!)
        make(request: request) { json, error in closure?(json, error) }
    }
}

URLSession示例的使用

private lazy var dataManager = DataManager(queue: DispatchQueue(label: "DataManager.queue", qos: .utility))
// .......
dataManager.searchRequest(term: "jack johnson") { json, error  in
      print(error ?? "nil")
      print(json ?? "nil")
      print("Update views")
}

结果