Tagging creates a link between your post and a tagged person's Facebook Timeline. This tagging option is available on the iPhone's Facebook app whenever you post a status update or photo. Previously posted photos can also be edited to tag people. Regardless of your privacy settings on a photo, a tagged person is always able to view the photo. A tagged person may also receive a notification of the tag, depending on his notification settings.
Tagging Status Updates
Log in to your Facebook account through your iPhone's Facebook app and open your News Feed.
Tap "Status" at the top of your News Feed and then write the text for the status update.
Tap the "Tag Friends" icon, which looks like a silhouetted person, to open the Tag Friends pop-up.
Tap "Search," type a friend's name and then tap the friend from the search results. Repeat to tag multiple people.
Tap "Done" when you finish adding tags and then "Post" to submit your status update.
Tagging New Photos
Log in to your Facebook account from the Facebook app.
Tap "Photo" from the top of your News Feed. If you haven't already enabled the Facebook app to access your iPhone photos, return to your home screen and tap "Settings | Privacy | Photos | Facebook" and toggle the switch to the On position.
Tap the new message icon under the photo. Enter the text for the photo update.
Tap the "Tag Friends" icon at the bottom of the status message.
Type the friend's name in the search field and then tap the appropriate search result to add the tag.
Tap "Post" to add the photo and status update to your Timeline.
Adding Tags to Existing Photos
Log in to your Facebook account from your iPhone's Facebook app and then open your Timeline.
Tap a photo on your Timeline to open the editing window. Alternatively, tap "Photos," select an album and then tap a photo to edit it.
Tap the "Tag" icon and then touch the person's face you want to tag.
Enter the person's name in the search field and select the appropriate search results.
Tap "Done" when complete.