If you don’t know How To Tag On Facebook using an iOS device then you must follow these steps:-

The first is to launch the Facebook app.

Now tap on the + icon in the top right corner.

Then tap on the Photo/Video option.

Now select the image that you want to upload and tap on Edit.

Then tap on the Tag photo icon.

Now type the name of the person that you want to tag.

Then select the name and tap on Done.