Apply automaticallyAdjustsScrollViewInsets in child view controller like Container View or UIPageViewController

YPLayoutGuideHelper.m

//
// YPLayoutGuideHelper.m
//
// Created by Yuya Tanaka, 2015
// 
// This is free and unencumbered software released into the public domain.
// Refer: http://unlicense.org/
//
// automaticallyAdjustsScrollViewInsets doesn't work for child view controllers
// hosted by something like Container View or UIPageViewController.
// This method manually setups insets from parent view controller.
//

#import "YPLayoutGuideHelper.h"

@implementation YPLayoutGuideHelper

/// Setups content inset of scroll view on child view controller.
/// Call this from viewWillLayoutSubviews of child view controller.
/// Any kind of scroll views (e.g. UITableView, UICollectionView, webView.scrollView) are accepted.
/// If passed view controller is NOT a child view controller or automaticallyAdjustsScrollViewInsets is disabled,
/// this method does nothing.
+ (void)setupInsetForScrollView:(UIScrollView *)scrollView onChildViewController:(UIViewController *)viewController
{
    if (!viewController.automaticallyAdjustsScrollViewInsets) {
        return;
    }
    UIViewController *currentViewController = viewController;
    UIViewController *rootParentViewController;
    while (currentViewController.parentViewController) {
        currentViewController = currentViewController.parentViewController;
        if ([currentViewController isKindOfClass:[UITabBarController class]] ||
            [currentViewController isKindOfClass:[UINavigationController class]] ||
            [currentViewController isKindOfClass:[UIPageViewController class]]) {
            continue;
        }
        rootParentViewController = currentViewController;
    }
    if (!rootParentViewController) {
        return;
    }

    // http://stackoverflow.com/a/21541533/1474113
    CGFloat topLength = rootParentViewController.edgesForExtendedLayout & UIRectEdgeTop ?
        rootParentViewController.topLayoutGuide.length : 0;
    CGFloat bottomLength = rootParentViewController.edgesForExtendedLayout & UIRectEdgeBottom ?
        rootParentViewController.bottomLayoutGuide.length : 0;
    UIEdgeInsets insets = UIEdgeInsetsMake(topLength, 0.0, bottomLength, 0.0);
    scrollView.contentInset = scrollView.scrollIndicatorInsets = insets;
}

@end

YPLayoutGuideHelper.swift

//
// YPLayoutGuideHelper.swift
//
// Created by Yuya Tanaka, 2016
//
// This is free and unencumbered software released into the public domain.
// Refer: http://unlicense.org/
//
// automaticallyAdjustsScrollViewInsets doesn't work for child view controllers
// hosted by something like Container View or UIPageViewController.
// This method manually setups insets from parent view controller.
//

import Foundation
import UIKit

final class YPLayoutGuideHelper: NSObject {

    /// Setups content inset of scroll view on child view controller.
    /// Call this from viewWillLayoutSubviews of child view controller.
    /// Any kind of scroll views (e.g. UITableView, UICollectionView, webView.scrollView) are accepted.
    /// If passed view controller is NOT a child view controller or automaticallyAdjustsScrollViewInsets is disabled,
    /// this method does nothing.
    class func setupInsetForScrollView(scrollView: UIScrollView, onChildViewController viewController: UIViewController) {
        if (!viewController.automaticallyAdjustsScrollViewInsets) {
            return
        }
        var currentViewController = viewController
        var candidateRootParentViewController: UIViewController? = nil
        while let viewController = currentViewController.parentViewController {
            currentViewController = viewController
            if viewController is UITabBarController ||
                viewController is UINavigationController ||
                viewController is UIPageViewController {
                continue
            }
            candidateRootParentViewController = viewController
        }
        guard let rootParentViewController = candidateRootParentViewController else { return }
        
        // http://stackoverflow.com/a/21541533/1474113
        let topLength = rootParentViewController.edgesForExtendedLayout.contains(.Top) ?
            rootParentViewController.topLayoutGuide.length : 0
        let bottomLength = rootParentViewController.edgesForExtendedLayout.contains(.Bottom) ?
            rootParentViewController.bottomLayoutGuide.length : 0
        let insets = UIEdgeInsets(top: topLength, left: 0.0, bottom: bottomLength, right: 0.0)
        scrollView.contentInset = insets
        scrollView.scrollIndicatorInsets = insets
    }
}