Networking and Persistence with JSON in Swift 4 (Part 2)

Thank you all for the great feedback on the previous article! Some of you wanted to know more about different networking requests and alternative persistence methods, so hopefully I can shed some more light on the matter with this article. If you haven’t already, I recommend reading Part 1 to learn a bit about making a simple GET request to JSONPlaceholder, converting the response data to structs, and saving those structs to disk.

Networking — making a POST request using structs

Carrying on the example from Part 1, we’ll start out with a struct representation of a Post on JSONPlaceholder’s simple REST API:

And let’s say we want to submit a Post to our cool API:

First we would need to use JSONEncoder to encode our Codable struct into JSON data, which we would then place in our URLRequest’s HTTP body.

After we submit our Post…

… we should receive this response from JSONPlaceholder:

Now that you know how to make GET and POST requests, making PUT, PATCH, and DELETE requests should be a piece of cake 🍰

Cool ways to persist structs on disk

In Part 1, I briefly went over how to store Post structs onto the user’s disk using Foundation’s built in storage helper methods. As per some of your requests, here are a few other ways of tackling the same problem.

Disk 💾

A delightful little framework I created to make persistence on iOS simple and fun, checkout it out on GitHub!

For all the other ways, we’ll be using this helper method to retrieve a URL to the user’s documents directory:

FileManager 😎

Besides Disk, this is my favorite way to handle JSON data. FileManager gives you a lot of access to information about files anywhere you have access to, respective file permissions, etc.

NSKeyedArchiver/NSKeyedUnarchiver 👵🏻

Streams (Output and Input streams) 🤓

Instead of dealing with buffers and mutating a Data instance, we could alternatively use Apple’s JSONSerialization class which handles all this work for us. Although it can seem a bit redundant, it looks much prettier:

Conclusion

I think it’s awesome that Apple has devoted so much time and manpower to making our lives as developers easier. In the old days, persisting data structures to disks was a hassle, and with the introduction of value-type structures in Swift, working with & managing data models has never been easier or as fun. Gone are the days of reference-typed data structures 🎉🎊🎉

Networking with the provided built-in classes in Foundation has also never been as robust and simple as it is today either. URLSession is becoming easier to use and hunky frameworks like Alamofire & Moya are going to go obsolete before you know it.

Feel free to reach out to me on Twitter with your thoughts, or if you need any help :)