Xamarin.iOS MemoryUtility

.View

using System;
using System.Collections.Generic;
using System.Linq;
using MonoTouch.MessageUI;
using MonoTouch.UIKit;

namespace MyApp
{
    public interface ICanCleanUpMyself
    {
        void CleanUp();
    }

    public static class MemoryUtility
    {
        public static void ReleaseUIViewWithChildren(UIView view, bool enableSelfCleaning = true)
        {
            try
            {
                if (view == null)
                    return;

                if (view.Subviews != null)
                {
                    view.Subviews
                        .ToList()
                        .ForEach(subview => 
                            ReleaseUIViewWithChildren(subview, enableSelfCleaning)
                    );
                }

                ReleaseObject(view, enableSelfCleaning);
            }
            catch (Exception exception)
            {
                // Logging ...
            }
        }

        public static void ReleaseObject(IDisposable disposableObject, bool enableSelfCleaning = true)
        {
            try
            {
                if (disposableObject == null)
                    return;

                ReleaseUIImageView(disposableObject);
                ReleaseUIButton(disposableObject);
                ReleaseUIView(disposableObject);
                ReleaseUINavigationController(disposableObject);
                ReleaseUIPageviewController(disposableObject);
                ReleaseUIViewController(disposableObject);
        
                if (enableSelfCleaning)
                    LetObjectCleanUpItself(disposableObject);

                disposableObject.Dispose();
            }
            catch (Exception exception)
            {
                // Logging ...
            }
        }

        public static void ReleaseObject<T>(WeakReference<T> weakReference, 
                                            bool enableSelfCleaning = true) where T : class, IDisposable
        {
            T reference;
            if (weakReference == null ||
                !weakReference.TryGetTarget(out reference) || reference == null)
                return;

            ReleaseObject(reference, enableSelfCleaning);
        }

        public static void ReleaseUITableViewCell(IDisposable disposableObject)
        {
            try
            {
                var cell = disposableObject as UITableViewCell;

                if (cell == null)
                    return;

                ReleaseUIViewWithChildren(cell.BackgroundView);
                ReleaseUIViewWithChildren(cell.SelectedBackgroundView);
                ReleaseUIViewWithChildren(cell.AccessoryView);
                ReleaseUIViewWithChildren(cell.ContentView);
            }
            catch (Exception exception)
            {
                // Logging ...
            }
        }

        public static void ReleaseSubviews(UIView[] subviews)
        {
            try
            {
                if (subviews == null || subviews.Length == 0)
                    return;

                foreach (UIView subview in subviews)
                {
                    if (subview is UIActivityIndicatorView)
                        continue;

                    if (subview != null)
                        ReleaseSubviews(subview.Subviews);

                    ReleaseObject(subview);
                }
            }
            catch (Exception exception)
            {
                // Logging ...
            }
        }

        private static void ReleaseUIButton(IDisposable disposableObject)
        {
            var button = disposableObject as UIButton;

            if (button == null)
                return;

            if (button.ImageView != null)
                ReleaseUIImageView(button.ImageView);

            if (button.CurrentBackgroundImage != null)
                button.CurrentBackgroundImage.Dispose();

            if (button.CurrentImage != null)
                button.CurrentImage.Dispose();
        }

        private static void ReleaseUIImageView(IDisposable disposableObject)
        {
            var imageView = disposableObject as UIImageView;

            if (imageView == null || imageView.Image == null)
                return;

            imageView.Image.Dispose();
            imageView.Image = null;
        }

        private static void ReleaseUINavigationController(IDisposable disposableObject)
        {
            var navigationController = disposableObject as UINavigationController;

            if (navigationController == null)
                return;

            if (navigationController is MFMailComposeViewController)
                return;

            ReleaseChildControllers(navigationController.ChildViewControllers);
        }

        private static void ReleaseUIPageviewController(IDisposable disposableObject)
        {
            var pageViewController = disposableObject as UIPageViewController;

            if (pageViewController == null)
                return;

            var children = pageViewController.ChildViewControllers
                .Union(pageViewController.ViewControllers)
                .ToList();

            ReleaseChildControllers(children);

            pageViewController.RemoveFromParentViewController();
        }

        private static void ReleaseChildControllers(IEnumerable<UIViewController> children)
        {
            foreach (UIViewController child in children)
            {
                var baseDialog = child as BaseDialog;

                if (baseDialog != null)
                {
                    if (!baseDialog.IsDead)
                    {
                        baseDialog.DetachEventHandlers();
                        baseDialog.CleanUpAfterDisappearing();
                        baseDialog.CleanUp();

                        child.RemoveFromParentViewController();
                        child.Dispose();
                    }

                    continue;
                }

                var timelineDialog = child as TimelineDialog;

                if (timelineDialog != null)
                {
                    timelineDialog.DetachEventHandlers();
                    timelineDialog.CleanUp();

                    timelineDialog.RemoveFromParentViewController();
                    timelineDialog.Dispose();

                    continue;
                }

                ReleaseUIViewWithChildren(child.ViewIfLoaded);
                ReleaseObject(child);
            }
        }

        private static void ReleaseUIViewController(IDisposable disposableObject)
        {
            var viewController = disposableObject as UIViewController;

            if (viewController == null || viewController is UINavigationController || viewController is UIPageViewController)
                return;

            ReleaseUIViewWithChildren(viewController.ViewIfLoaded);

            foreach (UIViewController child in viewController.ChildViewControllers)
            {
                ReleaseObject(child);
            }

            viewController.RemoveFromParentViewController();
        }

        private static void ReleaseUIView(IDisposable disposableObject)
        {
            var view = disposableObject as UIView;

            if (view == null || view.Superview == null)
                return;

            view.RemoveFromSuperview();
        }

        private static void LetObjectCleanUpItself(IDisposable dispoableObject)
        {
            var selfCleaningObject = dispoableObject as ICanCleanUpMyself;

            if (selfCleaningObject == null)
                return;

            selfCleaningObject.CleanUp();
        }
    }
}

License (MIT)

Copyright (c) 2015, 2018, Thomas Bandt (https://thomasbandt.com)

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

This is great. We are having Memory problems on our Xamarin.iOS app and going through a bunch of things like this. Unfortunately this snippet includes BaseDialog in a key method which I cannot find anyways and has no documentation. Any thoughts?