Networking with URLSession
Nov 28 2017 · Video Course (3 hrs, 28 mins) · Intermediate
Learn how to use URLSession, Apple's networking API, including when and how to use data, download and upload tasks, with or without a custom session delegate, and how the system manages background sessions. Keep your users' data safe with authentication and App Transport Security, and pick up tips for networking architecture, testing and metrics. Updated for iOS 11 and Swift 4.
Version
- Swift 4, iOS 11, Xcode 9


HTTP 101
11:54Learn some HTTP basics to make the most of URLSession, and discover the easy way to create URL objects from Strings.
URLSession
15:51The URLSession API has many moving parts: learn about URLSessionConfigurations, URLSessionTasks and delegates, and how they fit together.
URLSession Cookbook 1
12:24Learn about REST and JSON, then create a URLSession data task that makes a GET request on a REST API, and parses the JSON URLResponse.
Learn about URLRequest and HTTP headers, then create a URLSessionDataTask to POST to a REST API. Also build an Alamofire-inspired PostRouter to create URLRequests.
Download and Upload Task
11:40Learn about URLSessionDownloadTask and URLSessionUploadTask to save results to a file, or upload a data object or a file.
Background Sessions
29:55Download and upload tasks can run in a background session. Find out how the system handles this, and learn some advice and tips for long-running tasks.
ATS
25:49Learn what your app needs to do to support Apple's requirement for App Transport Security.
OperationQueue
10:58URLSession is an OperationQueue, and delegate and completion methods run on another OperationQueue: learn how to customize the delegate queue.
Architecture
15:24MVC shouldn't mean Massive View Controller: learn some ways to move networking code out of the view controller, and how to wrap a session task in an Operation.
Testing and Metrics
23:13Writing unit tests is A Good Thing: learn how to test asynchronous network code. And find out how to access URLSessionTaskMetrics transaction data.
Conclusion
4:03Review what you've learned in this video course, and get a TODO list for discussions with your back-end server team.
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