vdhamer / SwiftyJSON_demo

Code for Paul Hudson's (Hacking with Swift) [Project 38](https://www.hackingwithswift.com/read/38/). It integrates CoreData with JSON parsing via SwiftyJSON. The UI uses UIKit.

Functionality and purpose

This is Project 38 from Hacking with Swift by Paul Hudson.

Functionally, this demo app loads the 100 most recent commits from a Github repo via Github's API. It then merges these entries into a persistent on-device data store and displays the list of commits as a scrolling list (with basic Master/Detail functionality).

The project was designed by Paul Hudson as a learning vehicle. So, because it is a technology demonstrator, both screens don't even have a title ;-)

Compatibility

The app runs on iPhone, iPad and on MacOS (in "Designed for iPad" or "Mac Catalyst" modes). The app require iOS 16.0, because one line of code (UIPopoverPresentationControllerDelegate.sourceItem) needs iOS 16.0. If you don't need iPad support and want pre-iOS 16 support, try commenting out that line and changing the list of Supported Destinations accordingly.

Technologies

Technically the app uses:

1. SwiftyJSON - used to parse the JSON data format and convert the data into a Swift-friendly format.
2. CoreData - an abstracted version of SQLite. Somewhat outdated because Swift will gradually migrate to SwiftData.
3. UIKit - Apple's original framework to build user interfaces. It is arguably outdated by the newer SwiftUI. The Hacking with Swift lessons for Project 38 assume that you are reasonably proficient in Swift and are reasonably familiar with SwiftUI.

For my current personal project, I needed to combine SwiftyJSON, CoreData, and SwiftUI instead of SwiftyJSON, CoreData, and UIKit. Fortunately I already have the CoreData and SwiftUI working together nicely. So the use of UIKit isn't an issue for me: my SwiftUI code already displays a sectioned table with data fetched from CoreData. So I only needed to focus on how to use SwiftJSON to enter data into the CoreData persistent data storage.

My code changes

There are only minor changes compared to the original source code. This repo deliberately doesn't want to add functionality because Project 38 is an educational vehicle. So here I...

• ensured there are no warnings when using the lateset version of Swift/Xcode.
• did some renaming of variables (Hacking with Swift sometimes uses short names for practical reasons)
• installed SwiftLint 0.53 (with default settings) and fixed the warnings from SwiftLint (mainly about line lengths)
• installed SwiftJSON as a package rather than copying the Swift source file into the project. This updated SwiftyJSON to the latest version and keeps the package up to date.
• made changes to logging to the console and error handling. I deliberately used fatalError() instead of print() here and there, as this is not meant to be production code. FatalError ensures that such exceptions, if there were to show up, get attention.
• One of the projects filters (predicates) now finds commits by Doug Gregor instead of Joe Groff. Joe Groff nowadays appears to work on other projects. So filtering on Doug usually gives non-empty results (the app only loads records from the last few days).
• I added one line of code that allows the code to run on an iPad. It sets ac.popoverPresentationController?.sourceItem to anchor the Filter menu popup.

The "plus" version

The final code changes from the Hacking with Swift Project 38 are included in file ViewControllerPlus.swift. That file is a drop-in alternative to the simpler file ViewController.swift.

The changes consist of two advanced features that Paul Hudson called "optional". Those feataure are:

1. added Sections to the UITableView (grouping commits by the same author). This impacts the CoreData and UIKit part of the code.
2. updated the CoreData > UITableView interface to read records on demand (lazy loading) rather than loading all records from CoreData into UIKit up front.

The latter modification shouldn't be too relevant if you plan to use SwiftUI/CoreData/SwiftyJSON rather than UIKit/CoreData/SwiftyJSON because SwiftUI's List and ForEach views together automatically provide lazy loading.

To switch between ViewController and ViewControllerPlus.swift, select each of the files and enable/disable the file's Target Membership in the File Inspector panel. If both (or neither) files are selected, you will get a built-time error from the compiler.

I realize that the Plus version could have been achieved more elegantly by forking the original repository and making the required changes in the forked repo. But Github only allows you to fork repo's owned by someone else. I also looked into having multiple targets within a single Xcode project. That probably could work, but would add complexity.

Acknowledgments and licensing

• Almost all the code is from Project 38 of Hacking with Swift. Paul Hudson's Hacking with Sift code is the public domain without any restrictions whatsover (Unlicense).
• JSON parsing uses the SwiftyJSON/SwiftyJSON package.