NSURLSession with Token Authentication

Question

I have the following code in my iOS project and I want to convert to use NSURLSession instead of NSURLConnection. I am querying a REST API which uses a token-based HTTP Authentication scheme but I cannot find an example of how to do it.

NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:url]];

NSString *username = [[NSUserDefaults standardUserDefaults] stringForKey:@"Username"];

NSString *token = //GET THE TOKEN FROM THE KEYCHAIN


NSString *authValue = [NSString stringWithFormat:@"Token %@",token];
[request setValue:authValue forHTTPHeaderField:@"Authorization"];


if ([NSURLConnection canHandleRequest:request]){
    [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:YES];
    [NSURLConnection sendAsynchronousRequest:request queue:self.fetchQueue
                           completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {

                               if (!connectionError) {
                                   NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *)response;
                                   if (httpResponse.statusCode == 200){
                                       NSDictionary *jsonData = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers|NSJSONReadingAllowFragments error:nil];

                                       //Process the data
                                   }
                               }

                           }];
}

Answer 1

You can rewrite it using NSURLSession as follows

    [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:YES];

    NSString *token ; //GET THE TOKEN FROM THE KEYCHAIN

    NSString *authValue = [NSString stringWithFormat:@"Token %@",token];

    //Configure your session with common header fields like authorization etc
    NSURLSessionConfiguration *sessionConfiguration = [NSURLSessionConfiguration defaultSessionConfiguration];
    sessionConfiguration.HTTPAdditionalHeaders = @{@"Authorization": authValue};

    NSURLSession *session = [NSURLSession sessionWithConfiguration:sessionConfiguration];

    NSString *url;
    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:url]];

    NSURLSessionDataTask *task = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
        [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:NO];
        if (!error) {
            NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *)response;
            if (httpResponse.statusCode == 200){
                NSDictionary *jsonData = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers|NSJSONReadingAllowFragments error:nil];

                //Process the data
            }
        }

    }];
    [task resume];

Answer 2

This is in Swift, but the logic is the same:

    let sessionConfig = NSURLSessionConfiguration.defaultSessionConfiguration()
    let url  = NSURL(string: "some url")

    let request = NSMutableURLRequest(URL: url!)
    request.setValue("value", forHTTPHeaderField: "header field")

    let urlSession = NSURLSession(configuration: sessionConfig, delegate: self, delegateQueue: NSOperationQueue.mainQueue())


    let dataTask = urlSession.dataTaskWithRequest(request) { (data: NSData?, response: NSURLResponse?, error: NSError?) -> Void in
    }

    dataTask.resume()

Answer 3

Set the Authorization header on your URLSession configuration, or directly on your request.

Be advised that Apple says you "should not" attempt to modify the Authorization header in your URLSession configuration:

An URLSession object is designed to handle various aspects of the HTTP protocol for you. As a result, you should not modify the following headers:

• Authorization

• ...

It is, however, possible. If you want to do this, ensure that you set the header configuration before you create the URLSession. It's not possible to modify headers on an existing URLSession.

Here is a Swift playground that shows different scenarios:

import Foundation

// 1: Wrong -- mutating existing config for existing URLSession is no-op

var session = URLSession.shared
session.configuration.httpAdditionalHeaders = ["Authorization": "123"]

let url = URL(string: "https://postman-echo.com/get")!

session.dataTask(with: url) { (data, resp, err) in
    if let data = data {
        let str = String(bytes: data, encoding: .utf8)!
        let _ = str
    }
}.resume() // no authorization header

// 2: Setting headers on an individual request works fine.

var request = URLRequest(url: url)
request.addValue("456", forHTTPHeaderField: "Authorization")
session.dataTask(with: request) { (data, resp, err) in
    if let data = data {
        let str = String(bytes: data, encoding: .utf8)!
        let _ = str
    }
}.resume() // "headers": { "authorization": "456" }

// 3: You can set headers on a new URLSession & configuration

var conf = URLSessionConfiguration.default
conf.httpAdditionalHeaders = [
    "Authorization": "789"
]
session = URLSession(configuration: conf)

session.dataTask(with: url) { (data, resp, err) in
    if let data = data {
        let str = String(bytes: data, encoding: .utf8)!
        let _ = str
    }
}.resume() // "headers": { "authorization": "789" }