Objectvie-C / Swift interoperability issue. Failable initializer for objc enum doesn't work as expected.

objc-enum-in-swift.swift

// This creates UIViewAnimationCurve with invalid rawValue. 
// Should be exeption while unwrapping optional value.
let curve = UIViewAnimationCurve(rawValue: 9)!

// Prints "ease in out" (This is a first variant in the enum).
switch curve {
case .EaseInOut:
    print("ease in out")
case .EaseIn:
    print("ease in")
case .EaseOut:
    print("ease out")
case .Linear:
    print("linear")
}

// Equility doesn't work in this case.
// assert(curve == .EaseInOut)

// Equility using hashValue works as expected.
assert(curve.hashValue == UIViewAnimationCurve.EaseInOut.hashValue)

// Hacky way to create objc enum variant using hashValue.
assert(UIViewAnimationCurve(rawValue: (UIViewAnimationCurve(rawValue: 9) ?? .EaseInOut).hashValue) == .EaseInOut)