Swift 3.0

Question

我正在编写一个库，所以不使用UIKit，即使在我的iOS应用程序中，相同的代码也可以工作，但是当我在命令行中执行时，不会使用UKit。在PlayGround中它似乎也有效。

由于某种原因，回调没有被触发，因此打印语句没有执行。

internal class func post(request: URLRequest, responseCallback: @escaping (Bool, AnyObject?) -> ()) {
    execTask(request: request, taskCallback: { (status, resp)  -> Void in
            responseCallback(status, resp)
    })
}

internal class func clientURLRequest(url: URL, path: String, method: RequestMethod.RawValue,  params: Dictionary<String, Any>? = nil) -> URLRequest {
    var request = URLRequest(url: url)
    request.httpMethod = method
    do {
        let jsonData = try JSONSerialization.data(withJSONObject: (params! as [String : Any]), options: .prettyPrinted)

        request.setValue("application/json; charset=utf-8", forHTTPHeaderField: "Content-Type")
        request.httpBody = jsonData
    } catch let error as NSError {
        print(error)
    }
    return request
}

private class func execTask(request: URLRequest, taskCallback: @escaping (Bool,
    AnyObject?) -> ()) {

    let session = URLSession(configuration: URLSessionConfiguration.default)
    print("THIS LINE IS PRINTED")
    let task = session.dataTask(with: request, completionHandler: {(data, response, error) -> Void in
        if let data = data {
            print("THIS ONE IS NOT PRINTED")
            let json = try? JSONSerialization.jsonObject(with: data, options: [])
            if let response = response as? HTTPURLResponse , 200...299 ~= response.statusCode {
                taskCallback(true, json as AnyObject?)
            } else {
                taskCallback(false, json as AnyObject?)
            }
        }
    })
    task.resume()
}

编辑 - ：我正在编写一个库，所以不使用UIKit，即使在我的iOS应用程序中，相同的代码也可以工作，但是当我在命令行中执行时，不会。在PlayGround中它似乎也有效。

Answer 1

我从头开始制作一个简单的应用程序。（Xcode 8 beta 6 / swift 3）在控制器中我粘贴了你的代码。（加上网址创建..）我在调试器中看到了所有内容：

这一个是打印的

这一个是打印的，太多了

我回来了

所以看起来很有效。

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let URLString = "https://apple.com"
        let url = URL(string: URLString)
        let request = URLRequest(url: url!)


        ViewController.execTask(request: request) { (ok, obj) in

            print("I AM BACK")

        }

    }

    private class func execTask(request: URLRequest, taskCallback: @escaping (Bool,
        AnyObject?) -> ()) {

        let session = URLSession(configuration: URLSessionConfiguration.default)
        print("THIS LINE IS PRINTED")
        let task = session.dataTask(with: request, completionHandler: {(data, response, error) -> Void in
            if let data = data {
                print("THIS ONE IS PRINTED, TOO")
                let json = try? JSONSerialization.jsonObject(with: data, options: [])
                if let response = response as? HTTPURLResponse , 200...299 ~= response.statusCode {
                    taskCallback(true, json as AnyObject?)
                } else {
                    taskCallback(false, json as AnyObject?)
                }
            }
        })
        task.resume()
    }

}

Answer 2

这里是否有变化，现在有效。

Using NSURLSession from a Swift command line program

var sema = DispatchSemaphore( value: 0 )

private func execTask(request: URLRequest, taskCallback: @escaping (Bool,
    AnyObject?) -> ()) {

    let session = URLSession(configuration: URLSessionConfiguration.default, delegate: self, delegateQueue: nil )

    session.dataTask(with: request) {(data, response, error) -> Void in
        if let data = data {
            let json = try? JSONSerialization.jsonObject(with: data, options: [])
            if let response = response as? HTTPURLResponse , 200...299 ~= response.statusCode {
                taskCallback(true, json as AnyObject?)
            } else {
                taskCallback(false, json as AnyObject?)
            }
        }
    }.resume()
    sema.wait()
}

Answer 3

我知道答案已经很晚了但是如果你没有弄清楚问题或者在其他地方遇到问题，那就试试吧。

您需要将方法变量保存在方法范围之外（使其成为实例变量）。由于您在函数范围内在本地定义它。它可以在调用完成处理程序之前取消分配，记住完成处理程序不能保留你的会话对象，并且在执行运行循环之后，垃圾收集器将释放你的会话对象。每当我们想要从委托或完成处理程序回调时，我们都需要保留这些对象。

self.session = URLSession(configuration: URLSessionConfiguration.default)

Answer 4

let dataTask = session.dataTask(with: request, completionHandler: {data, response,error -> Void in 
    print("Request : \(response)")

    let res = response as! HTTPURLResponse

    print("Status Code : \(res.statusCode)")

    let strResponse = NSString(data: data!, encoding: String.Encoding.utf8.rawValue)
    print("Response String :\(strResponse)")
    })
dataTask.resume()

Answer 5

Swift 3.0

只需将以下代码复制到视图控制器中即可。

@IBAction func btnNewApplicationPressed (_ sender: UIButton) {
        callWebService()
}

func callWebService() {
    // Show MBProgressHUD Here
    var config                              :URLSessionConfiguration!
    var urlSession                          :URLSession!

    config = URLSessionConfiguration.default
    urlSession = URLSession(configuration: config)

    // MARK:- HeaderField
    let HTTPHeaderField_ContentType         = "Content-Type"

    // MARK:- ContentType
    let ContentType_ApplicationJson         = "application/json"

    //MARK: HTTPMethod
    let HTTPMethod_Get                      = "GET"

    let callURL = URL.init(string: "https://itunes.apple.com/in/rss/newapplications/limit=10/json")

    var request = URLRequest.init(url: callURL!)

    request.timeoutInterval = 60.0 // TimeoutInterval in Second
    request.cachePolicy = URLRequest.CachePolicy.reloadIgnoringLocalCacheData
    request.addValue(ContentType_ApplicationJson, forHTTPHeaderField: HTTPHeaderField_ContentType)
    request.httpMethod = HTTPMethod_Get

    let dataTask = urlSession.dataTask(with: request) { (data,response,error) in
        if error != nil{
            return
        }
        do {
            let resultJson = try JSONSerialization.jsonObject(with: data!, options: []) as? [String:AnyObject]
            print("Result",resultJson!)
        } catch {
            print("Error -> \(error)")
        }
    }

    dataTask.resume()
}

Answer 6

有时候，对我来说，在这些情况下未调用完成处理程序的解决方案是因为Info.plist上的“允许任意加载”标志被定义为“否”。

Allow Arbitrary loads flag defined as YES

Swift 3，没有调用URLSession dataTask completionHandler

6 个答案:

Swift 3.0