正从URL数据斯威夫特

Question

我试图从服务器&下载JSON文件下面的教程来做到这一点（http://www.learnswiftonline.com/mini-tutorials/how-to-download-and-read-json/）

首先我想“检查响应”部分（我加了一些部分，看看有什么错）

let requestURL: NSURL = NSURL(string: "http://www.learnswiftonline.com/Samples/subway.json")! 
let urlRequest: NSMutableURLRequest = NSMutableURLRequest(URL: requestURL) 
let session = NSURLSession.sharedSession() 
let task = session.dataTaskWithRequest(urlRequest) { 
    (data, response, error) -> Void in 

     let httpResponse = response as! NSHTTPURLResponse 
     let statusCode = httpResponse.statusCode 

     if (statusCode == 200) { 
      print("Everyone is fine, file downloaded successfully.") 
     } else { 
      print("Failed") 
     } 

task.resume() 

这应该打印或者“每个人都精〜”或“失败”，但也不来了......我想看到的StatusCode所以我把里面print(statusCode)但task再次打印什么。

这是我的操场截图：

+

CFRunLoop in Swift Command Line Program

这就是我一直在寻找的答案，因为我正在处理OS X命令行应用程序（我把整个一堆搬到了操场上，看看会发生什么）。检查这个，如果你与我相同

Answer 1

你看不到任何东西，因为dataTaskWithRequest是异步的，你的操场在'task.resume（）`后停止。异步任务不会执行更改。

您可以在最后调用该方法，task.resume后：

XCPlaygroundPage.currentPage.needsIndefiniteExecution = true 

也 '进口XCPlayground'，这样的事情：

import Foundation 
import XCPlayground 

let requestURL: NSURL = NSURL(string: "http://www.learnswiftonline.com/Samples/subway.json")! 
let urlRequest: NSMutableURLRequest = NSMutableURLRequest(URL: requestURL) 
let session = NSURLSession.sharedSession() 
let task = session.dataTaskWithRequest(urlRequest) {(data, response, error) -> Void in 

    let httpResponse = response as! NSHTTPURLResponse 
    let statusCode = httpResponse.statusCode 

    if (statusCode == 200) { 
    print("Everyone is fine, file downloaded successfully.") 
    } else { 
    print("Failed") 
    } 

} 
task.resume() 

XCPlaygroundPage.currentPage.needsIndefiniteExecution = true 

这篇文章可能有助于澄清更多： How do I run Asynchronous callbacks in Playground

编辑：

在Sw ift 3，这个改变了一下。

import PlaygroundSupport 
PlaygroundPage.current.needsIndefiniteExecution = true 

Answer 2

工作正常，在我的项目后，我改变了“HTTP” - > HTTPS，苹果宣布“应用传输安全”为iOS 9和OSX 10.11埃尔卡皮坦

let requestURL: NSURL = NSURL(string: "https://www.learnswiftonline.com/Samples/subway.json")! 
    let urlRequest: NSMutableURLRequest = NSMutableURLRequest(URL: requestURL) 
    let session = NSURLSession.sharedSession() 
    let task = session.dataTaskWithRequest(urlRequest) { 
     (data, response, error) -> Void in 

     let httpResponse = response as! NSHTTPURLResponse 
     let statusCode = httpResponse.statusCode 

     if (statusCode == 200) { 
      print("Everyone is fine, file downloaded successfully.") 
     } else { 
      print("Failed") 
     } 
    } 
     task.resume() 

HTTP响应：

<NSHTTPURLResponse: 0x7a670300> { URL: https://www.learnswiftonline.com/Samples/subway.json } { status code: 200, headers { 
"Content-Encoding" = gzip; 
"Content-Type" = "application/json"; 
Date = "Tue, 16 Feb 2016 07:43:05 GMT"; 
"Last-Modified" = "Sat, 14 Nov 2015 08:21:26 GMT"; 
Server = "cloudflare-nginx"; 
"Set-Cookie" = "__cfduid=d9d92befe8746168b2b291f5bfb8996081455608585; expires=Wed, 15-Feb-17 07:43:05 GMT; path=/; domain=.learnswiftonline.com; HttpOnly"; 
"cf-ray" = "27579e989ad5208a-KIX"; 

}}

或错误，如果使用HTTP

Domain=NSURLErrorDomain Code=-1022 "The resource could not be loaded because the App Transport Security policy requires the use of a secure connection." UserInfo={NSErrorFailingURLStringKey=http://www.learnswiftonline.com/Samples/subway.json, NSErrorFailingURLKey=http://www.learnswiftonline.com/Samples/subway.json, NSLocalizedDescription=The resource could not be loaded because the App Transport Security policy requires the use of a secure connection., NSUnderlyingError=0x7866de20 {Error Domain=kCFErrorDomainCFNetwork Code=-1022 "(null)"}})