URLSession Calls in Swift 3.0.1

URLSession Calls in Swift 3.0.1

func makeGetCall() {
// Set up the URL request
  let todoEndpoint: String = "https://jsonplaceholder.typicode.com/todos/1"
  guard let url = URL(string: todoEndpoint) else {
    print("Error: cannot create URL")
    return
  }
  let urlRequest = URLRequest(url: url)
  
  // set up the session
  let config = URLSessionConfiguration.default
  let session = URLSession(configuration: config)
  
  // make the request
  let task = session.dataTask(with: urlRequest) {
    (data, response, error) in
    // check for any errors
    guard error == nil else {
      print("error calling GET on /todos/1")
      print(error)
      return
    }
    // make sure we got data
    guard let responseData = data else {
      print("Error: did not receive data")
      return
    }
    // parse the result as JSON, since that's what the API provides
    do {
      guard let todo = try JSONSerialization.jsonObject(with: responseData, options: []) as? [String: AnyObject] else {
        print("error trying to convert data to JSON")
        return
      }
      // now we have the todo, let's just print it to prove we can access it
      print("The todo is: " + todo.description)
      
      // the todo object is a dictionary
      // so we just access the title using the "title" key
      // so check for a title and print it if we have one
      guard let todoTitle = todo["title"] as? String else {
        print("Could not get todo title from JSON")
        return
      }
      print("The title is: " + todoTitle)
    } catch  {
      print("error trying to convert data to JSON")
      return
    }
  }
  
  task.resume()
}

thinking of throwing this inside a simple swift docker container as a hello world example.

docker pull swiftdocker/swift
docker run --privileged -i -t --name swiftfun swiftdocker/swift:latest /bin/bash

tried running on https://swiftlang.ng.bluemix.net/#/repl
but it throws

Error running code:
WARNING: Your kernel does not support swap limit capabilities, memory limited without swap.
/swiftfiles/doit.sh: line 51: 40 Trace/breakpoint trap timeout ${TIMEOUT} .build/debug/TempCode

import Foundation
func makeGetCall() {
  // Set up the URL request
  let todoEndpoint: String = "https://jsonplaceholder.typicode.com/todos/1"
  guard let url = URL(string: todoEndpoint) else {
    print("Error: cannot create URL")
    return
  }
  let urlRequest = URLRequest(url: url)

  // set up the session
  let config = URLSessionConfiguration.default
  let session = URLSession(configuration: config)

  // make the request
  let task = session.dataTask(with: urlRequest) {
    (data, response, error) in
    // check for any errors
    guard error == nil else {
      print("error calling GET on /todos/1")
      print(error)
      return
    }
    // make sure we got data
    guard let responseData = data else {
      print("Error: did not receive data")
      return
    }
    // parse the result as JSON, since that's what the API provides
    do {
      guard let todo = try JSONSerialization.jsonObject(with: responseData, options: []) as? [String: AnyObject] else {
        print("error trying to convert data to JSON")
        return
      }
      // now we have the todo, let's just print it to prove we can access it
      print("The todo is: " + todo.description)

      // the todo object is a dictionary
      // so we just access the title using the "title" key
      // so check for a title and print it if we have one
      guard let todoTitle = todo["title"] as? String else {
        print("Could not get todo title from JSON")
        return
      }
      print("The title is: " + todoTitle)
    } catch  {
      print("error trying to convert data to JSON")
      return
    }
  }

  task.resume()
}

makeGetCall()

Sorry, I haven't done any work with running Swift in docker containers.

It did run in docker for me, but I needed to do some changes on JSONSerialization casting to [String: Any]

func makeGetCall() {
// Set up the URL request
let todoEndpoint: String = "https://jsonplaceholder.typicode.com/todos/1"
guard let url = URL(string: todoEndpoint) else {
print("Error: cannot create URL")
return
}
let urlRequest = URLRequest(url: url)

// set up the session
let config = URLSessionConfiguration.default
let session = URLSession(configuration: config)

// make the request
let task = session.dataTask(with: urlRequest) {
    (data, response, error) in
    
    if let data = data {
        print(String(data: data, encoding: .utf8) ?? "NO DATA")
    }
    
    if let response = response {
        print(response)
    }
    
    // check for any errors
    guard error == nil else {
        print("error calling GET on /todos/1")
        print(error!)
        return
    }
    // make sure we got data
    guard let responseData = data else {
        print("Error: did not receive data")
        return
    }
    // parse the result as JSON, since that's what the API provides
    do {
        guard let todo = try JSONSerialization.jsonObject(with: responseData, options: []) as? [String: Any] else {
            print("error trying to convert data to JSON")
            return
        }
        // now we have the todo, let's just print it to prove we can access it
        print("The todo is: " + todo.description)
        
        // the todo object is a dictionary
        // so we just access the title using the "title" key
        // so check for a title and print it if we have one
        guard let todoTitle = todo["title"] as? String else {
            print("Could not get todo title from JSON")
            return
        }
        print("The title is: " + todoTitle)
    } catch  {
        print("failed to serialize data to JSON")
        return
    }
}

task.resume()

}

Hi,

Not sure what's going on but this code doesn't print anything on the console. Am I missing something? Thanks.

V

Same here, I dont see anything on the console.

Same. No output.

If you're running in Playground, you might need to import PlaygroundSupport (assuming you're on Swift 3):

import PlaygroundSupport

and, at the end of your file add the following:

PlaygroundPage.current.needsIndefiniteExecution = true

No output either. Not in Playground but Swift project (Xcode 9.4.1)