如何在Swift中执行GET和POST请求？

时间：2015-06-26 16:29:57

标签： ios postgresql swift post strongloop

我是根据Ray Wenderlich的iOS Apprentice教程第4部分改编的。

此代码用作使用简单数据库模型发送到我的Strongloop API的GET请求，但是：

  1. 这样可行，但我不知道它为什么会起作用，因为它不会调用任何我可以看到实际发送请求的方法。

  2. 我认为无法将其变为POST请求。

    3. 我的问题是：如何执行POST请求？它是以完全不同的方式完成的吗？

    如果您需要更多信息，请与我们联系。

        class ViewController: UIViewController {


    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    @IBAction func getFromDB() {
        let url = urlWithSearchText("")
        println("URL: '\(url)'")
        if let jsonString = performGetRequestWithURL(url) {
            println("Received JSON string '\(jsonString)'")
        }
    }


    func urlWithSearchText(searchText: String) -> NSURL {
        let escapedSearchText = searchText.stringByAddingPercentEscapesUsingEncoding(NSUTF8StringEncoding)!
        let urlString = String(format: "http://localhost:3000/api/Tests", escapedSearchText)
        let url = NSURL(string: urlString)
        return url!
    }    

    func performGetRequestWithURL(url: NSURL) -> String? {
        var error: NSError?
        if let resultString = String(contentsOfURL: url, encoding: NSUTF8StringEncoding, error: &error) {
            return resultString
        } else if let error = error {
            println("Download Error: \(error)")
        } else {
            println("Unknown Download Error")
        }
        return nil
    }

    以下是这张照片的图片：

    https://dl.dropboxusercontent.com/u/14464971/Images/Messages%20Image%281477993527%29.png

7 个答案:

答案 0 :(得分：3)

以下是两种POST方法。取决于您是否希望它同步（其他所有内容等待post方法完成）或异步（POST方法在后台运行，其他方法并行运行）。

<强>方法 

// POST data to url
func postDataAsynchronous(url: String, bodyData: String, completionHandler: (responseString: String!, error: NSError!) -> ()) {
    var URL: NSURL = NSURL(string: url)!
    var request:NSMutableURLRequest = NSMutableURLRequest(URL:URL)
    request.HTTPMethod = "POST";
    request.HTTPBody = bodyData.dataUsingEncoding(NSUTF8StringEncoding);

    NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue.mainQueue()){

        response, data, error in

        var output: String!

        if data != nil {
            output = NSString(data: data, encoding: NSUTF8StringEncoding) as! String
        }

        completionHandler(responseString: output, error: error)
    }
}

// Obtain the data
func postDataSynchronous(url: String, bodyData: String, completionHandler: (responseString: String!, error: NSError!) -> ())
{
    let URL: NSURL = NSURL(string: url)!
    var request:NSMutableURLRequest = NSMutableURLRequest(URL:URL)
    request.HTTPMethod = "POST"
    request.HTTPBody = bodyData.dataUsingEncoding(NSUTF8StringEncoding);
    request.addValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")

    var response: NSURLResponse?
    var error: NSError?

    // Send data
    let data = NSURLConnection.sendSynchronousRequest(request, returningResponse: &response, error: &error)

    var output: String! // Default to nil

    if data != nil{
        output =  NSString(data: data!, encoding: NSUTF8StringEncoding) as! String
    }

    completionHandler(responseString: output, error: error)

}

使用

然后您可以这样调用（使用）它们：

postDataSynchronous(url, bodyData: bodyData) {
    responseString, error in

        if error != nil {
            println("Error during post: \(error)")
            return
        }
        else{
            //Success
            println(responseString)
            userType = responseString // Set usertype based on server response
        }        
    }

SWIFT 2.0 

func postData(url: String, params: Dictionary<String, String>, completionHandler: (data: NSData?, response: NSURLResponse?, error: NSError?) -> ()) {

    // Indicate download
    UIApplication.sharedApplication().networkActivityIndicatorVisible = true

    let url = NSURL(string: url)!
    //        print("URL: \(url)")
    let request = NSMutableURLRequest(URL: url)
    let session = NSURLSession.sharedSession()
    request.HTTPMethod = "POST"
    request.addValue("application/json", forHTTPHeaderField: "Content-Type")
    request.addValue("application/json", forHTTPHeaderField: "Accept")

    // Verify downloading data is allowed
    do {
        request.HTTPBody = try NSJSONSerialization.dataWithJSONObject(params, options: [])
    } catch let error as NSError {
        print("Error in request post: \(error)")
        request.HTTPBody = nil
    } catch {
        print("Catch all error: \(error)")
    }

    // Post the data
    let task = session.dataTaskWithRequest(request) { data, response, error in
        completionHandler(data: data, response: response, error: error)

        // Stop download indication
        UIApplication.sharedApplication().networkActivityIndicatorVisible = false // Stop download indication

    }

    task.resume()

}

答案 1 :(得分：3)

Swift 3＆amp;上述

获取 

private func httpRequest() {

    //create the url with NSURL
    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()
}

发表 

@IBAction func submitAction(sender: AnyObject) {

    //declare parameter as a dictionary which contains string as key and value combination. considering inputs are valid

    let parameters = ["name": nametextField.text, "password": passwordTextField.text] as Dictionary<String, String>

    //create the url with URL
    let url = URL(string: "http://myServerName.com/api")! //change the url

    //create the session object
    let session = URLSession.shared

    //now create the URLRequest object using the url object
    var request = URLRequest(url: url)
    request.httpMethod = "POST" //set http method as POST

    do {
        request.httpBody = try JSONSerialization.data(withJSONObject: parameters, options: .prettyPrinted) // pass dictionary to nsdata object and set it as request body

    } catch let error {
        print(error.localizedDescription)
    }

    request.addValue("application/json", forHTTPHeaderField: "Content-Type")
    request.addValue("application/json", forHTTPHeaderField: "Accept")

    //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)
                // handle json...
            }

        } catch let error {
            print(error.localizedDescription)
        }
    })
    task.resume()
}

答案 2 :(得分：0)

此方法调用http请求。

String(contentsOfURL: url, encoding: NSUTF8StringEncoding, error: &error)

因为Swift String没有这样的初始签名。

这个方法将写在项目的某个地方，extension的{​​{1}}

就像这样

String

答案 3 :(得分：0)

String（contentsOfUrl：encoding：error）初始化程序在引擎盖下发出GET请求，并将内容作为具有指定编码的字符串返回。

提出请求的一种方法是创建NSURLConnection并使用NSMutablrURLRequest将HTTP方法设置为帖子。使用NSMutableURLRequest，您可以创建NSURLConnection并立即使用委托启动它，也可以调用NSURLConnection.sendSynchronousRequest或NSURLConnection.sendAsynchronousRequest来发送请求。

答案 4 :(得分：0)

guard let url = URL(string: "https://jsonplaceholder.typicode.com/users") else { return }

    let session = URLSession.shared
    session.dataTask(with: url) { (data, response, error) in
        if let response = response {
            print(response)
        }

        if let data = data {
            print(data)
            do {
                let json = try JSONSerialization.jsonObject(with: data, options: [])
                print(json)
            } catch {
                print(error)
            }

        }
    }.resume()
}

这是一种获取方法。

答案 5 :(得分：0)

let parameters = ["username": "@Bipin_kumar", "tweet": "HelloWorld"]

guard let url = URL(string: "https://jsonplaceholder.typicode.com/posts") else { return }
var request = URLRequest(url: url)
request.httpMethod = "POST"
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
guard let httpBody = try? JSONSerialization.data(withJSONObject: parameters, options: []) else { return }
request.httpBody = httpBody

let session = URLSession.shared
session.dataTask(with: request) { (data, response, error) in
    if let response = response {
        print(response)
    }

    if let data = data {
        do {
            let json = try JSONSerialization.jsonObject(with: data, options: [])
            print(json)
        } catch {
            print(error)
        }
    }

}.resume()

这是一种后期方法。

答案 6 :(得分：0)

获取请求 

 func getRequest(with url: URL, callback: @escaping (Any?) -> Swift.Void) -> Void {

    let defaultConfigObject = URLSessionConfiguration.default
    defaultConfigObject.timeoutIntervalForRequest = 30.0
    defaultConfigObject.timeoutIntervalForResource = 60.0

    let session = URLSession.init(configuration: defaultConfigObject, delegate: nil, delegateQueue: nil)

    var urlRequest = URLRequest(url: url as URL)
    urlRequest.addValue("application/json", forHTTPHeaderField: "Content-Type")

    urlRequest.httpMethod = "GET"
    session.dataTask(with: urlRequest, completionHandler: { (data, response, error) in

        guard    let httpResponse: HTTPURLResponse = response as? HTTPURLResponse
            else {
                print("Error: did not receive data")
                return
              }

        var response : (Any)? = nil

        if httpResponse.statusCode == 200 {
            print(httpResponse)

            guard let responseData = data else {
                print("Error: did not receive data")
                return
            }

            do {
                let responseData = try JSONSerialization.jsonObject(with: responseData, options: [JSONSerialization.ReadingOptions.allowFragments])

                  response = responseData
                 callback(response)
            }
            catch _ as NSError {

                let responseString = NSString(data: data!, encoding: String.Encoding.utf8.rawValue)
                callback(responseString)
                return
            }
        }
        else {
            print(httpResponse)

            guard error == nil else {
                print("error calling GET on /todos/1")
                print(error ?? "error")
                callback(response!)
                return
            }

        }
    }).resume()
}

POST REQUEST 

//MARK: post request
func postRequest(with url:URL, postBody:String, callback: @escaping (Any?) -> Void) -> Void {

    let defaultConfigObject = URLSessionConfiguration.default
    defaultConfigObject.timeoutIntervalForRequest = 30.0
    defaultConfigObject.timeoutIntervalForResource = 60.0

    let session = URLSession.init(configuration: defaultConfigObject, delegate: nil, delegateQueue: nil)

    let params: String! = postBody

    var urlRequest = URLRequest(url: url as URL)
    urlRequest.httpMethod = "POST"

    let data = params.data(using: String.Encoding(rawValue: String.Encoding.utf8.rawValue))
    urlRequest.httpBody = data

    session.dataTask(with: urlRequest, completionHandler: { (data, urlResponse, error) in


        guard let httpResponse:HTTPURLResponse = urlResponse as? HTTPURLResponse
            else{
                print("did not get any data")
                return
            }
        var response : (Any)? = nil

        if httpResponse.statusCode == 200 {

            guard let responseData = data else {
                print("Error: did not receive data")
                return
            }

            do {
                guard let responseData = try JSONSerialization.jsonObject(with: responseData, options: []) as? [String: AnyObject] else {
                    print("error trying to convert data to JSON")
                    return
                }

                response = responseData
                callback(response)
            } catch _ as NSError {

                let responseString = NSString(data: data!, encoding: String.Encoding.utf8.rawValue)
                callback(responseString)
                return
            }
        }

        else {
        guard error == nil else {
            print("error calling GET on /todos/1")
            print(error ?? "error")
            callback(nil)
            return
        }
    }
    }).resume()
}

始终尝试检查HTTPURLResponse代码

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