Xcode 9.1 & Swift 4 support
This PR upgrades the project to be in line with Xcode 9.1 and Swift 4.
I am wondering what's the plan for this. Because as far as I know, Swift 4 already have native support for JSON encoding and decoding.
@yzhong52 my 2 cents. I use this library in a side project that is live in the Store. I don't have much time to spend on that project, moving to Swift's native Codable has little return of investment for me right now. That's why I forked the library to add Swift 4 support, so that I could still use it in that project without having to spend time migrating stuff that works already.
And looking at your diff, there is no code change at all for Swift 4?
@mokagio also it looks like the build doesn't pass with your changes. https://travis-ci.org/matthewcheok/JSONCodable/builds/300894536