I used the below extension methods to solve these memory leak issues. Think of Ender's Game final battle scene, the DisposeEx method is like that laser and it disassociates all views and their connected objects and disposes them recursively and in a way that shouldn't crash your app.

DisposeEx.cs

//https://stackoverflow.com/questions/25532870/xamarin-ios-memory-leaks-everywhere?rq=1

   public static void DisposeEx(this UIView view) {
        const bool enableLogging = false;
        try {
            if (view.IsDisposedOrNull())
                return;

            var viewDescription = string.Empty;

            if (enableLogging) {
                viewDescription = view.Description;
                SystemLog.Debug("Destroying " + viewDescription);
            }

            var disposeView = true;
            var disconnectFromSuperView = true;
            var disposeSubviews = true;
            var removeGestureRecognizers = false; // WARNING: enable at your own risk, may causes crashes
            var removeConstraints = true;
            var removeLayerAnimations = true;
            var associatedViewsToDispose = new List<UIView>();
            var otherDisposables = new List<IDisposable>();

            if (view is UIActivityIndicatorView) {
                var aiv = (UIActivityIndicatorView)view;
                if (aiv.IsAnimating) {
                    aiv.StopAnimating();
                }
            } else if (view is UITableView) {
                var tableView = (UITableView)view;

                if (tableView.DataSource != null) {
                    otherDisposables.Add(tableView.DataSource);
                }
                if (tableView.BackgroundView != null) {
                    associatedViewsToDispose.Add(tableView.BackgroundView);
                }

                tableView.Source = null;
                tableView.Delegate = null;
                tableView.DataSource = null;
                tableView.WeakDelegate = null;
                tableView.WeakDataSource = null;
                associatedViewsToDispose.AddRange(tableView.VisibleCells ?? new UITableViewCell[0]);
            } else if (view is UITableViewCell) {
                var tableViewCell = (UITableViewCell)view;
                disposeView = false;
                disconnectFromSuperView = false;
                if (tableViewCell.ImageView != null) {
                    associatedViewsToDispose.Add(tableViewCell.ImageView);
                }
            } else if (view is UICollectionView) {
                var collectionView = (UICollectionView)view;
                disposeView = false; 
                if (collectionView.DataSource != null) {
                    otherDisposables.Add(collectionView.DataSource);
                }
                if (!collectionView.BackgroundView.IsDisposedOrNull()) {
                    associatedViewsToDispose.Add(collectionView.BackgroundView);
                }
                //associatedViewsToDispose.AddRange(collectionView.VisibleCells ?? new UICollectionViewCell[0]);
                collectionView.Source = null;
                collectionView.Delegate = null;
                collectionView.DataSource = null;
                collectionView.WeakDelegate = null;
                collectionView.WeakDataSource = null;
            } else if (view is UICollectionViewCell) {
                var collectionViewCell = (UICollectionViewCell)view;
                disposeView = false;
                disconnectFromSuperView = false;
                if (collectionViewCell.BackgroundView != null) {
                    associatedViewsToDispose.Add(collectionViewCell.BackgroundView);
                }
            } else if (view is UIWebView) {
                var webView = (UIWebView)view;
                if (webView.IsLoading)
                    webView.StopLoading();
                webView.LoadHtmlString(string.Empty, null); // clear display
                webView.Delegate = null;
                webView.WeakDelegate = null;
            } else if (view is UIImageView) {
                var imageView = (UIImageView)view;
                if (imageView.Image != null) {
                    otherDisposables.Add(imageView.Image);
                    imageView.Image = null;
                }
            } else if (view is UIScrollView) {
                var scrollView = (UIScrollView)view;
                scrollView.UnsetZoomableContentView();
            }

            var gestures = view.GestureRecognizers;
            if (removeGestureRecognizers && gestures != null) {
                foreach(var gr in gestures) {
                    view.RemoveGestureRecognizer(gr);
                    gr.Dispose();
                }
            }

            if (removeLayerAnimations && view.Layer != null) {
                view.Layer.RemoveAllAnimations();
            }

            if (disconnectFromSuperView && view.Superview != null) {
                view.RemoveFromSuperview();
            }

            var constraints = view.Constraints;
            if (constraints != null && constraints.Any() && constraints.All(c => c.Handle != IntPtr.Zero)) {
                view.RemoveConstraints(constraints);
                foreach(var constraint in constraints) {
                    constraint.Dispose();
                }
            }

            foreach(var otherDisposable in otherDisposables) {
                otherDisposable.Dispose();
            }

            foreach(var otherView in associatedViewsToDispose) {
                otherView.DisposeEx();
            }

            var subViews = view.Subviews;
            if (disposeSubviews && subViews != null) {
                subViews.ForEach(DisposeEx);
            }                   

            if (view is ISpecialDisposable) {
                ((ISpecialDisposable)view).SpecialDispose();
            } else if (disposeView) {
                if (view.Handle != IntPtr.Zero)
                    view.Dispose();
            }

            if (enableLogging) {
                SystemLog.Debug("Destroyed {0}", viewDescription);
            }

        } catch (Exception error) {
            SystemLog.Exception(error);
        }
    }

    public static void RemoveAndDisposeChildSubViews(this UIView view) {
        if (view == null)
            return;
        if (view.Handle == IntPtr.Zero)
            return;
        if (view.Subviews == null)
            return;
        view.Subviews.ForEach(RemoveFromSuperviewAndDispose);
    }

    public static void RemoveFromSuperviewAndDispose(this UIView view) {
        view.RemoveFromSuperview();
        view.DisposeEx();
    }

    public static bool IsDisposedOrNull(this UIView view) {
        if (view == null)
            return true;

        if (view.Handle == IntPtr.Zero)
            return true;;

        return false;
    }

    public interface ISpecialDisposable {
        void SpecialDispose();
    }