AdaptiveStoryboard/AdaptiveStoryboard/UIViewController+ViewControllerShowing.swift

/*
Copyright (C) 2016 Apple Inc. All Rights Reserved.
See LICENSE.txt for this sample’s licensing information
 
Abstract:
An extension that gives information about how view controllers will be shown, for determining disclosure indicator visibility and row deselection.
*/
 
import UIKit
 
extension UIViewController {
    /**
        Returns whether calling `showViewController(_:sender:)` would cause a
        navigation "push" to occur.
    */
    func willShowingViewControllerPushWithSender(_ sender: AnyObject?) -> Bool {
        // Find and ask the right view controller about showing.
        if let target = targetViewController(forAction: #selector(UIViewController.willShowingViewControllerPushWithSender(_:)), sender: sender) {
            return target.willShowingViewControllerPushWithSender(sender)
        }
 
        // Or if we can't find one, we won't be pushing.
        return false
    }
 
    /**
        Returns whether calling `showDetailViewController(_:sender:)` would cause a
        navigation "push" to occur.
    */
    func willShowingDetailViewControllerPushWithSender(_ sender: AnyObject?) -> Bool {
        // Find and ask the right view controller about showing.
        if let target = targetViewController(forAction: #selector(UIViewController.willShowingDetailViewControllerPushWithSender(_:)), sender: sender) {
            return target.willShowingDetailViewControllerPushWithSender(sender)
        }
 
        // Or if we can't find one, we won't be pushing.
        return false
    }
}
 
extension UINavigationController {
    override func willShowingViewControllerPushWithSender(_ sender: AnyObject?) -> Bool {
        // Navigation Controllers always push for `showViewController(_:sender:)`.
        return true
    }
}
 
extension UISplitViewController {
    override func willShowingViewControllerPushWithSender(_ sender: AnyObject?) -> Bool {
        // Split View Controllers never push for `showViewController(_:sender:)`.
        return false
    }
    
    override func willShowingDetailViewControllerPushWithSender(_ sender: AnyObject?) -> Bool {
        if isCollapsed {
            /*
                If we're collapsed, re-ask this question as `showViewController(_:sender:)`
                to our primary view controller.
            */
            let target = viewControllers.last
        
            return target?.willShowingViewControllerPushWithSender(sender) ?? false
        }
 
        // Otherwise, we don't push for `showDetailViewController(_:sender:)`.
        return false
    }
}