How to hide Tab Bar on push in Xamarin.Forms?

Question

I\'m struggling for last few days with TabbedPage in Xamarin.Forms on iOS. I found some solutions like those: https://forums.xamarin.com/discussion/20901/hide-t

Answer 1

I managed to implement a solution which fixes the issue with blank space after hiding TabBar. You can read more details about it in this article.

To solve the problem we just need to layout all ChildViewControllers. Here is my sample implementation of a custom TabbedPage and its TabbedPageRenderer.

HideableTabbedPage.cs:

using System;
using Xamarin.Forms;

namespace HideTabBar.Controls
{
    public class HideableTabbedPage : TabbedPage
    {
        public static readonly BindableProperty IsHiddenProperty =
            BindableProperty.Create(nameof(IsHidden), typeof(bool), typeof(HideableTabbedPage), false);

        public bool IsHidden
        {
            get { return (bool)GetValue(IsHiddenProperty); }
            set { SetValue(IsHiddenProperty, value); }
        }
    }
}

HideableTabbedPageRenderer.cs:

using System;
using System.ComponentModel;
using System.Threading.Tasks;
using HideTabBar.Controls;
using HideTabBar.iOS.CustomRenderer;
using UIKit;
using Xamarin.Forms;
using Xamarin.Forms.Platform.iOS;

[assembly: ExportRenderer(typeof(HideableTabbedPage), typeof(HideableTabbedPageRenderer))]
namespace HideTabBar.iOS.CustomRenderer
{
    public class HideableTabbedPageRenderer : TabbedRenderer
    {
        private bool disposed;
        private const int TabBarHeight = 49;

        protected override void OnElementChanged(VisualElementChangedEventArgs e)
        {
            base.OnElementChanged(e);

            if (e.OldElement == null)
            {
                this.Tabbed.PropertyChanged += Tabbed_PropertyChanged;
            }
        }

        private void Tabbed_PropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            if (e.PropertyName == HideableTabbedPage.IsHiddenProperty.PropertyName)
            {
                this.OnTabBarHidden((this.Element as HideableTabbedPage).IsHidden);
            }
        }

        protected override void Dispose(bool disposing)
        {
            base.Dispose(disposing);
            this.disposed = true;
        }

        private async void OnTabBarHidden(bool isHidden)
        {
            if (this.disposed || this.Element == null || this.TabBar == null)
            {
                return;
            }

            await this.SetTabBarVisibility(isHidden);
        }

        private async Task SetTabBarVisibility(bool hide)
        {
            this.TabBar.Opaque = false;
            if (hide)
            {
                this.TabBar.Alpha = 0;
            }

            this.UpdateFrame(hide);

            // Show / Hide TabBar
            this.TabBar.Hidden = hide;
            this.RestoreFonts();

            // Animate appearing 
            if (!hide)
            {
                await UIView.AnimateAsync(0.2f, () => this.TabBar.Alpha = 1);
            }
            this.TabBar.Opaque = true;

            this.ResizeViewControllers();
            this.RestoreFonts();
        }

        private void UpdateFrame(bool isHidden)
        {
            var tabFrame = this.TabBar.Frame;
            tabFrame.Height = isHidden ? 0 : TabBarHeight;
            this.TabBar.Frame = tabFrame;
        }

        private void RestoreFonts()
        {
            // Workaround to restore custom fonts:

            foreach (var item in this.TabBar.Items)
            {
                var text = item.Title;
                item.Title = "";
                item.Title = text;
            }
        }

        private void ResizeViewControllers()
        {
            foreach (var child in this.ChildViewControllers)
            {
                child.View.SetNeedsLayout();
                child.View.SetNeedsDisplay();
            }
        }
    }
}  

Final result: