Update Swift 5

[CRoig]

Checklist

• [X] I've checked that all new and existing tests pass
• [x] I've updated the documentation if necessary
• [X] I've added an entry in the CHANGELOG to credit myself

Description

I have update Swift default version to 5.0

Motivation and Context

Updating project to Swift 5.0 removes a Carthage warning when updating packages using XCode 10.2.

***  Skipped installing OHHTTPStubs.framework binary due to the error:
    "Incompatible Swift version - framework was built with 4.2.1 (swiftlang-1000.11.42 clang-1000.11.45.1) and the local version is 5.0 (swiftlang-1001.0.69.5 clang-1001.0.46.3).

I built OHHTPPStubs using Carthage using Swift 5.0. Warning is not longer appearing. Also I verified the changes did not break any existing unit test.

[CRoig]

Updated README with Swift5 compatibility and added XCode 10.2 image to the rakefile. No change required on podspec since XCode 10.2 still supports 8.0 iOS.

[AliSoftware]

Thanks!

I just realized that indeed for OHHTTPStubs we haven't updated the podspec with the latest recommendations by CocoaPods as I thought we did. That's is, now CocoaPods supports a swift_version attribute that you can add to your podspec to indicate which version(s) of Swift is supported by the pod. In our case that would mean add this attribute to the 'Swift' subspec then.

That swift_version has been introduced in CocoaPods 1.4, and in CocoaPods 1.7 they introduced support for a range of Swift versions as well using swift_versions. So that migration of OHHTTPStubs to Swift 5 might be the occasion to take advantage of that in our podspec 😉

[AliSoftware]

Mmmh having SWIFT_VERSION set to 5.0 in the project prevents it to be built using older Xcodes, which is why the CI fails. We need to address that before considering merging

[jeffctown]

@AliSoftware Would you be cool using swift_version for this pull request, considering that Cocoapods 1.7.0 is still in beta? I think it makes sense to update to the ranged version of this parameter (swift_versions) after the new Cocoapods is fully released.

I like your suggestion to add swift_version to the Swift subspec, but don't think you can add that parameter to a subspec, or at least thats what Cocoapods complained about when I tried to add it there and use it in the Swift example. I saw this error (using Cocoapods v1.6.1):

As for getting CI to pass: We can just add the swift version as a rake parameter to override the project setting to set the swift version to 4.0 and 4.2. I have a branch that is passing using that method.

@CRoig would you be okay to grant me access to your fork? I'd like to update some of the project settings the swift migration added before we merge this in. I can also add the changes to get the CI passing.

[AliSoftware]

Yep looks like a good compromise indeed 👍

[CRoig]

@jeffctown No problem at all. I did not have the time yet to fix this. But feel free to fork and amend the PR. Thanks.

[jeffctown]

@AliSoftware looks good to me. Let me know what you think.

[AliSoftware]

🎉

[jeffctown]

@CRoig - I just finished the 8.0.0 release for Swift 5. Thanks for the help!

@eMdOS - FYI