I'm unable to read values from the Keychain when using the Swift compiler Optimization Level [Fastest -O], which is default for Release mode apps.
var returnedData: Unmanaged<AnyObject>? = nil
let results = Int(SecItemCopyMatching(query, &returnedData))
var returnedData: AnyObject?
var results = withUnsafeMutablePointer(&returnedData) { SecItemCopyMatching(query, UnsafeMutablePointer($0)) }