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)

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.

 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()

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)")
    }

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 ?? "")
    }
}