Make implicit units on TimeInterval explicit

[nick.keets]

Sure, here is another quote about a different feature request for Foundation:

@Philippe_Hausler

Additions to Foundation are not out of the question; they just require a bit more effort since we would want pairity between the objective-c implementation and the swift implementation. Internally to Cocoa we follow a very similar process to Swift evolution so a proposal written for swift-evo would be suitable to pass across to Cocoa as well. The only hitch to getting it done is that the maintainers of NSMeasurement and NSUnit would need to sign off on supporting the change and the proposal would have to be approved. In the end it just means a second level of process. If you are interested in giving that a go, write up a proposal using the swift evolution template and get me a link to it.

In any case I believe that my comment still stands about changes to Foundation requiring in the order of 5 years till they become realistically available.