Allow SwiftAA to be compiled and used on Linux

iKenndac commented 1 year ago

This is an in-progress PR that allows SwiftAA to be used on Swift on Linux. The complexity here is with the ObjC bridge — and, unfortunately it seems that the only way to do this in a sane way is to get rid of it and use C bindings instead.

I'm opening this PR early to get some feedback on what you think. The removal of ObjCAA is the large breaking change. SwiftAA is unchanged other than some minor internal type name tweaks. AA+ is completely untouched.

Changes

Removes Objective-C++ bindings in favour of C ones. The main change here is that KPCAADate is implemented using the handle pattern rather than as an NSObject subclass. All .mm files have been renamed to .cpp ones.
Removes all imports of Foundation.h in the bridge C code. NSInteger and NSUInteger are redefined for sanity, but BOOL is (somehow) more complicated, so all uses of BOOL have been changed to bool.
Guards some APIs (such as those requiring CoreLocation) behind appropriate checks. ObjC++ XCTestCase subclasses too.
Adds a platform-agnostic Color struct to use when AppKit or UIKit aren't available.

Still To Do

Tidy up — some doc comments are now incorrect, etc.
Decide what to do with ObjCAA. Right now, it's still called ObjCAA but it has no ObjC in it. It could be renamed CAA or something, breaking the library for anyone that uses ObjCAA. Or, it could be renamed to AABridge and exclusively be used by the Swift code, and ObjCAA can come back as it was for ObjC users.

Tests

All tests continue to pass on macOS. On Linux, there are eight failures. However, the values are so close I think it's a side effect of the different platforms (but I'm not an expert).

SaturnTests.swift:55: error: SaturnTests.testSaturnMoonsDetailsMimas : XCTAssertEqual failed: ("0.3181181493094037") is not equal to ("0.3181181493094038") -
SaturnTests.swift:56: error: SaturnTests.testSaturnMoonsDetailsMimas : XCTAssertEqual failed: ("-0.8325520387386532") is not equal to ("-0.8325520387386528") -
SaturnTests.swift:60: error: SaturnTests.testSaturnMoonsDetailsMimas : XCTAssertEqual failed: ("0.3181056446263968") is not equal to ("0.3181056446263969") -
SaturnTests.swift:61: error: SaturnTests.testSaturnMoonsDetailsMimas : XCTAssertEqual failed: ("-0.8325520387386532") is not equal to ("-0.8325520387386528") -
SaturnTests.swift:105: error: SaturnTests.testSaturnMoonsDetailsMimas : XCTAssertEqual failed: ("-0.971846971308554") is not equal to ("-0.9718469713085551") -
SaturnTests.swift:106: error: SaturnTests.testSaturnMoonsDetailsMimas : XCTAssertEqual failed: ("-3.136031295237765") is not equal to ("-3.1360312952377654") -
SaturnTests.swift:107: error: SaturnTests.testSaturnMoonsDetailsMimas : XCTAssertEqual failed: ("8.080062662295763") is not equal to ("8.080062662295765") -
SaturnTests.swift:110: error: SaturnTests.testSaturnMoonsDetailsMimas : XCTAssertEqual failed: ("-0.9724451111090852") is not equal to ("-0.9724451111090863") -
SaturnTests.swift:111: error: SaturnTests.testSaturnMoonsDetailsMimas : XCTAssertEqual failed: ("-3.137227671996788") is not equal to ("-3.1372276719967886") -
SaturnTests.swift:112: error: SaturnTests.testSaturnMoonsDetailsMimas : XCTAssertEqual failed: ("8.080062662295763") is not equal to ("8.080062662295765") -
SaturnTests.swift:156: error: SaturnTests.testSaturnMoonsDetailsMimas : XCTAssertEqual failed: ("-48.760383752635384") is not equal to ("-48.76038375263538") -
SaturnTests.swift:157: error: SaturnTests.testSaturnMoonsDetailsMimas : XCTAssertEqual failed: ("4.13716606895207") is not equal to ("4.137166068952069") -
SaturnTests.swift:158: error: SaturnTests.testSaturnMoonsDetailsMimas : XCTAssertEqual failed: ("32.737852943980215") is not equal to ("32.7378529439802") -
SaturnTests.swift:161: error: SaturnTests.testSaturnMoonsDetailsMimas : XCTAssertEqual failed: ("-48.835951923571486") is not equal to ("-48.83595192357148") -
SaturnTests.swift:162: error: SaturnTests.testSaturnMoonsDetailsMimas : XCTAssertEqual failed: ("4.143560854704697") is not equal to ("4.143560854704695") -
SaturnTests.swift:163: error: SaturnTests.testSaturnMoonsDetailsMimas : XCTAssertEqual failed: ("32.737852943980215") is not equal to ("32.7378529439802") -

onekiloparsec commented 1 year ago

Hi. Wow, impressive and interesting PR. I didn't know we could go with direct C bindings (it was quite some time ago).

Basically, I am very open to it, but I couldn't really help. I am running out of time almost everyday. I will keep following your work, and I'd be happy to merge once it is fully working.

Even if it is quite some past work to be removed, removing one layer is probably simpler / better in the long run.

I'd be curious to know for what application you intend to use SwiftAA on Linux.

iKenndac commented 1 year ago

@onekiloparsec No worries about not being able to help — I just wanted to check in and get your opinions on a couple of things, and make sure you'd be open to such a big change. It sounds like you're OK with the ObjCAA going away?

We're building an app called Photo Scout (https://photo-scout.app) that's a tool for photographers to be told when the conditions are right for a photo they want to take. There's a fair amount of astronomy maths that needs to be done for features like "Tell me when the sun is in this position in the sky" etc.

The Linux requirement comes from having a shared Swift "engine" that runs both in the app and in the backend (that's deployed on Linux) to power notifications. So far we've been finding calculations around the internet and porting them to Swift, but it's a bit haphazard and we're going to make a mistake at some point — so I figure it's a better use of our efforts to support a project like this.

onekiloparsec commented 1 year ago

Very interesting. I am happy if this library is useful to others, that's the whole point of OSS, I think. I originally created SwiftAA hoping it will help building a new version of my native application called iObserve. I never managed to develop this app, because I focused on the web version.

So it's great if it used by others.

I confirm I am OK to remove the ObjCAA layer. It was quite some work, but it has no real additional value, it only serves as a bridge.

iKenndac commented 1 year ago

Ok great, I'll continue tidying up and I'll ping you again when it's ready for review/merge.

iKenndac commented 1 year ago

@onekiloparsec Hi again! Sorry for the big delay.

I've performed some more work on this, and I think I'm very close to having this ready to merge. As of right now, I've:

Merged in the latest work from master.
Fixed the build from every angle I can build it from: SPM on both Mac and Linux, CocoaPods (via pod lib lint), and the Xcode project all build correctly now.
Fixed the build on watchOS and tvOS.
Removed the ObjCAA target in favour of AABridge, as discussed above. There's now a big hole for ObjCAA to come back if it turns out someone relied on it.
Bumped the version to 3.0.0. The Swift API is completely unchanged, but the removal of ObjCAA technically makes this a breaking change, hence the major version bump.

If you're happy with this, I can update the README/docs to remove mentions of ObjCAA and we can merge it in.

vincentneo commented 1 year ago

By the way,

Adds a platform-agnostic Color struct to use when AppKit or UIKit aren't available.

Maybe it would be a good idea to take this opportunity to rename the Color struct/typealias. Not that it conflicts with anything but that it might cause confusion with SwiftUI's Color. (In the case where someone uses SwiftAA in a SwiftUI-based project)

iKenndac commented 1 year ago

@vincentneo Since it's a typealias, it won't interfere. The struct is only defined when both UIKit and AppKit aren't available, and currently SwiftUI is very much tied to UIKit and AppKit. However, I changed it anyway.

As well as Color, SwiftAA declares a lot of types that interfere with other things (like Day, Hour, etc). There's a lot of import struct Time.Day etc going on in my project already! Color has never been a problem though.

@onekiloparsec I've updated the README. I think this is ready for merge now.

onekiloparsec commented 9 months ago

Sorry for the delay. I can't test it right now, but it looks very good. Let's merge it.

iKenndac commented 9 months ago

@onekiloparsec Thank you for coming back to this, I appreciate it!

The app I was talking about above was launched in September and this branch is being used in production in both the iOS app and the Swift on the Server backend on Linux. It's been working great! https://photo-scout.app

onekiloparsec commented 9 months ago

I just had a look at your app/service. Really beautiful, we can see it's well crafted.

It is somewhat similar to what I am currently implementing myself for Arcsecond.io (but for a very different usage). :-)

onekiloparsec / SwiftAA