Support Project Catalyst (running iPad apps on macOS)

[brunolemos]

Apple has just announced Project Catalyst on WWDC 2019, which allows iOS/iPad apps to run on macOS without modification. This is AWESOME.

We'd love if React Native could build and work correctly on macOS. That should be a supported scenario.

Beta is already available today for developers to test.
EDIT: Stable version of macOS Catalina is already available.

https://techcrunch.com/2019/06/03/ios-apps-will-run-on-macos-with-project-catalyst/

[brunolemos]

Not sure if should open an issue here or on react-native: facebook/react-native#25133

[David-Melo]

Didn't they also announce iPadOS? How does this affect react-native now that iOS and IPadOS might be two separate targets

[kelset]

Ok, so let's keep the discussion here, it fits better the format.

Few points (which ofc take with a pinch of salt):

• I feel that the likely outcome is that it will be something closer to react-native-tvos in terms of implementation than it being integrated in the main repo. (same answer for the new ipados)

• as you mentioned, they literally announced this less than 24hrs ago so I don't see this happening for a while

• this going into the main repo is mostly a decision that needs to happen internally at Facebook, because they need to evaluate if it fits with their needs first (hence why my first point) - so cc'ing @TheSavior @cpojer @fkgozali so that they can give some insight on their POV

• Just for reference, there was already some experimentation from @wbroek https://twitter.com/wbroek/status/1102361241811599365?s=20 and similarly, this is what MS has been doing for their macos implementation: https://twitter.com/LinguaBrowse/status/1102504112552374273

[pvinis]

I mean.. there is no Facebook.app for the mac right?? And it would be nice to reuse the iOS code, right? wink wink? :p

[wbroek]

That it can work I and some more people demonstrated but took some adjustments in the core of React Native; mostly deprecated API's because you must target the latest iOS/Mac.
So fully agree with @kelset that Facebook as to have a need because of the core changes; although with the Lean initiative a lot of old balast will be removed.

Planned to make a POC in the coming weeks with 0.60 to see what is working and needed change

[fungilation]

Ya I'm looking for docs and experience on this. How automatic is such "porting" from iPad to Mac?

Relevant, important links while I was researching this:

• Dimensions window support for Split View and Slide Over on iPad facebook/react-native#16152
• https://github.com/wix/react-native-navigation/blob/master/docs/docs/layout-types.md#splitview-ios-only
• https://developer.apple.com/design/human-interface-guidelines/ios/overview/ipad-apps-for-mac/

I disagree about treating ipadOS support in RN like tvOS. The latter is very different, while ipadOS is for all intents and purposes of app makers, the same as iOS 13. Dimensions window support for Split View and Slide Over on iPad in #16152 link above means afaik, I got what I need to fully convert my iPhone RN app to support the iPad's screen. Add splitView so my 1 column iPhone layout become 2 columns, then it should be ready for the new Catalyst conversion for macOS.

Apple's new HIG docs for iPad apps on Mac says explicitly that splitView on iPad will get automatic conversion to equivalent on macOS.

So this is my own plan for bringing my iPhone app (WonderSwipe) to iPad and Mac. Am I missing anything that needs RN core support to make happen, or am I right that all the pieces are already in place as I've outlined above? RNN provides the splitView, while Xcode 11 provides not just iPad layout but also a new Mac option you simply turn on. Will share hiccups I get along the way.

Anyone else thinking/planning something similar, on iPad/Mac adaptations of your RN apps? What else do you see missing inside RN that's needed for these adaptations?

[radex]

I feel that the likely outcome is that it will be something closer to react-native-tvos in terms of implementation than it being integrated in the main repo. (same answer for the new ipados)

I strongly disagree.

tvOS is treated by Apple as a separate OS, with most things in common with iOS and UIKit, but a separate target nonetheless.

iPadOS is only a marketing term. It's not really a separate OS, from a technical standpoint.

UIKit for Mac / Marzipan / Catalyst is a weird beast, but the way Apple treats it, Mac is only a separate device target for the iOS app. It's not listed as a separate OS in code (all platform checks reference iOS, not macOS), and you're not really supposed to create a separate Xcode target for Catalyst apps (the way you are for tvOS or watchOS -- or truly native/AppKit Mac apps), just check the checkbox, add necessary configuration for macOS, and if necessary -- add extra target environment checks in code to ifdef APIs not available on macOS/outside of macOS.

Therefore, the core of RN for Catalyst apps should remain the same, and in the same repo. A react-native-community repo(s) might (and should) spring up for enhancing Catalyst apps (supporting extra features only available for the Mac).

[kelset]

👋 Radek - yeah, again, my was literally just a feeling because I wasn't really able to understand what iPad OS really was back then.

Upon further investigation, and your comment, I can rollback that 100%, yeah it's basically still iOS13 from our perspective 🤗

[radex]

Heads up: I began initial for for supporting Catalyst in React Native. More work needs to be done to polish everything to look good, but in general it was an hour or two of work to get it to compile properly:

facebook/react-native#25427