You might have tried to play a Battle Royale game on mobile, but you were probobly disappointed. Today, Fortnite published an article talking about iOS port of Fortnite. You can find the post here.
We don't yet know the release date yet but sign-ups will start on Monday, March 12. According to Epic, app is fully compatible with PC/Mac and PS4. This means you can play with your friends in a squad game even if they use PC. They also promise the game will be same as other versions. Note that this does not include Save the World.
To play the game, you will need at least iPhone 6S/SE running iOS 11. Or you can use your iPad mini 4 / iPad pro / iPad air 2 and any other iPad that was released in 2017.
To get the game, you need to sign-up on the Fortnite website after March 12. Participants will receive an email with the link to get Fortnite on their mobile device. Players who get the email will also get an invite code to share with their friends. There might be a limited number of players allowed for early access so make sure to sign-up as soon as possible.
For android users, app will be released after a few months, probobly on June. We will try to get the app too. And if we do, there will be an update blog reviewing the app.
Have a nice day and good luck!