Iphone Website Redirects to Porn

Some hacks behave that way – these should help you clean them up:

https://codex.www.ads-software.com/FAQ_My_site_was_hacked
https://www.ads-software.com/support/topic/268083#post-1065779
https://smackdown.blogsblogsblogs.com/2008/06/24/how-to-completely-clean-your-hacked-wordpress-installation/
https://ottopress.com/2009/hacked-wordpress-backdoors/

Additional Resources:
https://sitecheck.sucuri.net/scanner/
https://www.unmaskparasites.com/
https://blog.sucuri.net/2012/03/wordpress-understanding-its-true-vulnerability.html

Thanks for those links, I have had a read through them, but as I am new to wordpress I have limited knowledge. All three of my websites:

https://www.neverup-neverin.com
https://www.markjamesgolfcoaching.com
https://www.ontargettdesign.com

Have the same problem- when I go onto them on ipad or iphone they redirect to porn, yet when I visit the site on a laptop they appear fine?

How could they do all three websites at once? And also are there any simple step by step manuals out there that will ensure I can get the sites back to normal?

Thanks in advance

How could they do all three websites at once?

Hackers rarely attack just one site. They will try to attack all sites on a server or with a particular host.

The links posted above are the simplest but most effective way to clean your sites out.