I have wanted this method to exist since Swift 1. I realized this morning that there was no reason that it couldn't.

EmptyOrNil.swift

extension Optional where Wrapped: Collection  {
    /*
    NOTE: Since this extends Optional rather than the possible collection,
    you don't use the "?" when calling it `isEmptyOrNil()`
    Example:
      var myString: String? = ""
      myString.isEmptyOrNil  // Evaluates to true.
      myString = nil
      myString.isEmptyOrNil  // Also evaluates to true.
      myString?.isEmptyOrNil // Will not compile.
    */
    
    var isEmptyOrNil: Bool {
        switch self {
        case .some(let collection):
            return collection.isEmpty
        case .none:
            return true
        }
    }
    
    /*
    This allows you to use nil coalescing to on a string, whether it's nil or just empty. 
    Example:
      var myString: String? = ""
      var nonNilString: String = myString.nilIfEmpty() ?? "WOOT"  // nonNilString will equal "WOOT"
      myString = nil
      nonNilString: String = myString.nilIfEmpty() ?? "NEATO"     // nonNilString will equal "NEATO"
    */
    
    func nilIfEmpty() -> Wrapped? {
        return isEmptyOrNil ? nil : self!
    }
}