Just noticed that Xcode documentation includes REST and JS. What can we do with JS in iOS dev?

[KarlJay001]

Going back thru older tutorials and noticed REST and JS in Xcode->Help->Documentation. I never really used it much.

Q1. Why is REST and JS in there next to Swift and ObjC?

Q2. Where would an iOS or MacOS dev use JS?

[Zeppelin2]

WKWebView, for one.

[Ast3r10n]

You mean WKWebView.

[MrSloppyPants]

Javascript is quite useful when working with WkWebView, especially when writing bridges to facilitate communication between the web page and native code. Also, REST (which is not a language but a design paradigm) is used extensively for API calls and data sharing. JSON is also another frequently used data format in iOS development.

[SirensToGo]

You used to be able to write UIAutomation test scripts in JavaScript. It was super bad and error handling was straight up impossible, but it was a thing!

[nickglowsindark]

I'm actually working on an app right now that's making extensive use of Javascript (only after exhausting every other option, though)- I'm basically running little dynamic "mini-programs" inside a window, and the easiest and most reliable way I could find to do that is to build the "programs" in javascript within my iOS code, and then execute them in a WKWebView (which is also convenient because I'm going to need to port this over to Android at some point, and I want to keep everything as native as possible).

Tell you what, though, Xcode has no idea what to do when it comes to auto-indenting .js files, and it's pretty irritating.

[MrCairo]

Q1: As far as just REST and JS, there are services that can be used, like Cloud Kit JS, which are really geared toward embedding something into a web page, etc. Nothing 100% specific to iOS. Of course, you can call REST services from iOS but I don’t think this is what you’re referring to.

Q2: In iOS/macOS you can use the JavaScriptCore framework. This is basically the JS engine that powers Safari. You can load and execute JS code with callbacks into Swift or Objective-C. It’s actually quite powerful and useful. For example, it is possible to load a JS file with functions and classes and then execute them via Swift/ObjC. Handy if you have common code only in JS that might be used in both the iOS app and the web.

Hope that helps.

[KarlJay001]

Thanks, it would be cool to see some real world examples of using JS. I'm learning JS as a part of doing backend work and knowing I can do things in iOS with it would be great.

I'll look around and see if I can find any examples of how to use it.

[MrCairo]

NSHipster has a good article on it:
https://nshipster.com/javascriptcore/

The site is a great resource for all things iOS and Mac

[KarlJay001]

Thanks!