This would need to go through the Swift Evolution Process.

This looks like it could be covered by SE-0089's LosslessStringConvertible

https://github.com/apple/swift-evolution/blob/master/proposals/0089-rename-string-reflection-init.md

Comment by Markus Hanauska (JIRA)

You seriously want to add a complete language feature, just because it helps you with one very specific use case? A use case that most people never face as they will use a ready-to-use JSON parser for such a task? And that all for a feature you could implement yourself with maybe 10 lines of code? Yup, that's also a way to bloat a language beyond good and evil. If we start like that, then we must add another 2 million features that only server maybe one single use case and that each could have easily be implemented by the programmer himself. Where can I downvote on this?

Comment by Pascal (JIRA)

This works in Swift 3 (but does not tolerate spelling variants as proposed by OP).

Welcome to Apple Swift version 3.0.1 (swiftlang-800.0.58.6 clang-800.0.42.1). Type :help for assistance.
  1> Bool("true")
$R0: Bool? = true
  2> Bool("false")
$R1: Bool? = false
  3> Bool("TrUE")
$R2: Bool? = nil
  4> Bool(" true ")
$R3: Bool? = nil
  5> Bool("1")
$R4: Bool? = nil
  6> Bool("Y")
$R5: Bool? = nil
  7> Bool("whatever")
$R6: Bool? = nil