After seeing this, I can't be the only one who got curious as to how many emojis there actually are on iOS.
Obviously, a quick google doesn't work right now.
So I did this to try to figure out: emojipedia.org, the site that supposedly breaks google, has a page that appears to show all the available emojis on iOS [1]. On this page, all except the first 21 emojis are displayed in a way that uses lazy loading of the images. These images are contained in <li class="lazyparent"> elements. Assuming that there are no other <li class="lazyparent"> elements on the page, we should get the number of emojis on iOS simply by counting those elements.
Opening up the console and running
document.getElementsByClassName('lazyparent').length
gives us 4037. So the total number of emojis on iOS should be 4037 + 21 = 4058. If the above method is correct, that is.