InitialAttitudeLayoutSubviews.swift

override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()

    /// viewDidLoad() is often too early to get the first initial attitude, so we use viewDidLayoutSubviews() instead
    if let currentAttitude = motionManager.deviceMotion?.attitude {
        /// we populate initialAttitude with the current attitude
        initialAttitude = currentAttitude
    }
}