Update to Swift 4.2

[rhysforyou]

This PR updates to SnapKit to build with Swift 4.2, which involves a few key changes:

• Update the Swift version in the project's build settings
• Update to recommended project settings as suggested by Xcode 10
• Removes the LayoutAttribute and LayoutRelation attributes used for cross platform compatibility, as now all platforms use NSLayoutConstraint.Attribute and `NSLayoutConstraint.Relation
• Specifies an explicit Swift version in the project's Podspec
• Updates the Swift Package Manager manifest to the latest format
• Update the Travis CI build script to use Xcode 10

I have Travis running against my fork of the repo, you can see build results here: https://travis-ci.org/rhysforyou/SnapKit

[spadafiva]

@rhysforyou I would love to see this added! Thanks for doing this.

[freak4pc]

I'm a bit confused with why you removed this code? Wouldn't this break support for anything below Swift 4.2 ?

[freak4pc]

Looking into the develop branch (and also just built for myself on my project) - this was already resolved in #543. Seems like this PR is not needed, let me know if you think otherwise?

[avery-pierce]

Sorry, I'm confused. It looks like issue #543 wasn't resolved?

In any case, I'm trying to use Swift 4.2 in my project, and as of now, adding SnapKit as a CocoaPods dependency causes my app to not compile. Using https://github.com/rhysforyou/SnapKit/tree/swift-4.2 as a remote dependency resolves it.

[freak4pc]

@aapierce0 Sorry, I meant #516, and I meant the develop branch.
Can you try adding:

pod 'SnapKit', git: 'https://github.com/SnapKit/SnapKit', branch: 'develop'

[avery-pierce]

@freak4pc Aha, that seems to work. Thanks!

[Kalvin126]

Could we set the spec.swift_version = '4.2' in the SnapKit.podspec as well?

[freak4pc]

I don't see why you'd want to do that. It'd break backward compatibility for Swift 4 projects.
Better to leave as is, in which case it would be based on the Project's version.

[Kalvin126]

I mean I'd wish the current podspec had spec.swift_version = '4.0', because my project is using Swift 4.2, but SnapKit and other pods are not yet 4.2 ready and CocoaPods is resolving to use my project's Swift version which is 4.2.

I do understand there are problems with both approaches. Right now, I'd have to have post install script to set SnapKit's swift version to 4.0

[freak4pc]

Did you read the comments to this thread? More specifically the one directing to the develop branch ?

[Kalvin126]

I did, but I'd rather point to tags instead of branches

[Panajev]

You can run a post pod install hook adding it in your Podfile and in there force maybe even all your pod to go in Swift 4/4.1 mode... you can do more advanced processing but debugging these kind of changes is a bit of trial and error using the Xcodeproj gem Cocoapods relies on.

…

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On 17 Sep 2018, at 22:26, Kalvin Loc ***@***.***> wrote: I did, but I'd rather point tags instead of branches — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub, or mute the thread.

[Kalvin126]

oh, spec.swift_version = '4.2' was actually added in this PR

[fassko]

@freak4pc

Maybe for older Swift versions we can set up branch or tag and include spec.swift_version = '4.2' in this new release?

[freak4pc]

@fassko I'm not sure what you mean exactly. I never saw a good reason to use spec.swift_version in the podspec level as I feel its a bit aggressive. If the project can be built on both Swift 4 and Swift 4.2, the absence of that is better so the decision is made by the project itself.

[fassko]

@freak4pc I think you're right, makes total sense. Thanks!

[freak4pc]

4.0.1 was released : https://github.com/SnapKit/SnapKit/releases/tag/4.0.1
I would close this PR If I were you, as it seems Xcode 10 backward-compatible support has been addressed.

[mattbarker016]

There's still a warning that SnapKit 4.0.1 needs to be converted to Swift 4.2 in Xcode.

[mattbarker016]

Why was this closed? There's still a warning that SnapKit 4.0.1 needs to be converted to Swift 4.2.

[likeSo]

[freak4pc]

This change is wrong @likeSo - These two definitions aren't supported below Swift 4.2.

[likeSo]

You mean NSLayoutConstraint.Relation can not be used on Swift 4.2?😀 But i can see that in Xcode:

SnapKit version in my Podfile is 4.0.1, and my project still needs to migrate:

After conversion, that two changes made...

[freak4pc]

Made a PR to fix the minor warning bothering y'all :) #547