HTTP Request in swift not working

问题:

I'm trying to learn about working with APIs in Swift. As a good first test, I figured I'd hit the itunes API and just return some search results. I'm in playground using the following code. I don't get any errors, but my println isn't outputting anything. Anyone know what's wrong?

Thanks!

import UIKit
import XCPlayground

XCPSetExecutionShouldContinueIndefinitely()


let url = NSURL(string: "https://itunes.apple.com/lookup?id=909253")

let task = NSURLSession.sharedSession().dataTaskWithURL(url!) {(data, response, error) in
    println(NSString(data: data, encoding: NSUTF8StringEncoding))
}

task.resume()

回答1:

Try adding this line of code:

URLCache.shared = URLCache(memoryCapacity: 0, diskCapacity: 0, diskPath: nil)

回答2:

For Swift 3/Xcode 8.2.1, combining a couple of the answers (rv1331, Wouter van Zuilen) gave the best results with no errors in Playground. I'm using this Swift 3 REST example:

http://mrgott.com/swift-programing/30-work-with-rest-api-in-swift-3-and-xcode-8-using-urlsession-and-jsonserialization

import PlaygroundSupport
import Foundation

PlaygroundPage.current.needsIndefiniteExecution = true
URLCache.shared = URLCache(memoryCapacity: 0, diskCapacity: 0, diskPath: nil)

回答3:

Swift 3 code:

<!-- language: lang-c -->

import PlaygroundSupport
PlaygroundPage.current.needsIndefiniteExecution = true

回答4:

try following line and i guess it will work:

XCPlaygroundPage.currentPage.needsIndefiniteExecution = true

回答5:

Not sure why you aren't seeing an error—I get this:

NSURLConnection/CFURLConnection HTTP load failed (kCFStreamErrorDomainSSL, -9807)

You can test more effectively with httpbin.org—this works perfectly for me:

let url = NSURL(string: "http://httpbin.org/get")

let task = NSURLSession.sharedSession().dataTaskWithURL(url!) {(data, response, error) in
    println(NSString(data: data, encoding: NSUTF8StringEncoding))
}

task.resume()

回答6:

My answer is not correct, it's really only the in the playgound indefinitite page execution. The session type does not matter.

Run into the same issue recently and found a solution.

The error is caused by using URLSession.shared() which apparently is not allowed in a playground sandbox.

Create and use your own ephemeral URL session instead:

let session = URLSession(configuration: URLSessionConfiguration.ephemeral)