The Grand Ivy has an iOS app, so the answer to "the grand ivy app ios" is yes: iPhone owners can use an app or the mobile site in the browser. The table above shows all three routes as available, and this page covers the iPhone one.
Using The Grand Ivy on an iPhone

On an iPhone, the casino comes in two forms. The iOS app is installed on the handset, and the mobile site opens in Safari or another browser without installing anything. Both are listed as available for The Grand Ivy, so you are choosing how to open the casino, not whether you can.
Compared with a computer, the main difference is the screen. An iPhone shows less at a time, so you scroll more and tap rather than click, and turning the phone sideways gives a wider view. Buttons sit close together on a small screen, so check the amount and the action before you confirm a deposit or a bet.
Choosing the app does not rule out the mobile version if you ever want the browser instead, and the app overview compares every route side by side. Before you decide, think about how much storage you have free and whether you want another icon on the home screen.
Finding and installing the iPhone app

Install it through the App Store, the only route you need on an iPhone. Open the store on your iPhone and look for the app there, and check who published it before you install it, as you would with any app that handles payments. You can also use visit The Grand Ivy to open the casino from your phone and start there.
Do not install a casino app from a link in a message, from an email or from a page you reached through an advert. If something asks you to install a profile or to change your phone's security settings, stop. The mobile site is the simpler alternative if the route to the app seems unclear.
After installing, you can sign in with your existing details through the login page or create an account through sign-up. Keep an eye on the permissions the app asks for, and allow only what you are comfortable with. If a permission has nothing to do with playing, decline it.
Practical points on an iPhone

Lock the phone with a passcode or Face ID or Touch ID, and keep notifications from your accounts private on the lock screen. If someone else can pick up your phone, they can open your casino account, so do not leave it unlocked.
Use your mobile data or a network you trust when you log in or make a payment, and avoid public Wi-Fi for anything involving your account. Keep iOS updates installed, because they carry security fixes.
Set your limits before you play. The safer gambling page explains the deposit limits, time-outs and self-exclusion you can use, and GAMSTOP covers all UK-licensed sites at once. Read the full terms of any offer before you deposit from your phone, exactly as you would on a computer. T&Cs apply.
