How do I make an HTTP request in Swift?

Question

I read The Programming Language Swift by Apple in iBooks, but cannot figure out how to make an HTTP request (something like cURL) in Swift. Do I need to import Obj-C classes or do I just need to import default libraries? Or is it not possible to make an HTTP request based on native Swift code?

Answer 1

You can use URL, URLRequest and URLSession or NSURLConnection as you'd normally do in Objective-C. Note that for iOS 7.0 and later, URLSession is preferred.

Using URLSession

Initialize a URL object and a URLSessionDataTask from URLSession. Then run the task with resume().

let url = URL(string: "http://www.stackoverflow.com")!

let task = URLSession.shared.dataTask(with: url) {(data, response, error) in
    guard let data = data else { return }
    print(String(data: data, encoding: .utf8)!)
}

task.resume()

Using NSURLConnection

First, initialize a URL and a URLRequest:

let url = URL(string: "http://www.stackoverflow.com")!
var request = URLRequest(url: url)
request.httpMethod = "POST" 

Then, you can load the request asynchronously with:

NSURLConnection.sendAsynchronousRequest(request, queue: OperationQueue.main) {(response, data, error) in
    guard let data = data else { return }
    print(String(data: data, encoding: .utf8)!)
}

Or you can initialize an NSURLConnection:

let connection = NSURLConnection(request: request, delegate:nil, startImmediately: true)

Just make sure to set your delegate to something other than nil and use the delegate methods to work with the response and data received.

For more detail, check the documentation for the NSURLConnectionDataDelegate protocol

Testing on an Xcode playground

If you want to try this code on a Xcode playground, add import PlaygroundSupport to your playground, as well as the following call:

PlaygroundPage.current.needsIndefiniteExecution = true

This will allow you to use asynchronous code in playgrounds.