Check if view controller is presented modally, or pushed on a navigation stack

Check_if_view_controller_is_presented_modally__or_pushed_on_a_navigation_stack.swift

// @see http://stackoverflow.com/a/23620428/1002412
// @see http://level49.com/119

override func viewWillAppear(animated: Bool) {
    super.viewWillAppear(animated)
    if isBeingDismissed() {
        // being dismissed
    } else if isMovingFromParentViewController() {
        // being poped
    } else {
        // 
    } 
}

override func viewWillDisappear(animated: Bool) {
    super.viewWillDisappear(animated)
    if isBeingPresented() {
        // being presented
    } else if isMovingFromParentViewController() {
        // being pushed
    } else {
        // simply showing again because another VC was dismissed
    } 
}