How to Use Auto-Correction and Predictive Text on Your iPhone | Smart Solutions.
To start setting up your text replacements, just open your Settings app and follow these steps:
1) Tap General ► Keyboard.
2) Tap Text Replacement.
3) Tap the plus sign on the top right. Note that this screen shows any text replacements that you set up.
4) Type in the phrase that you would like to shorten. For example, you may type in your email address, a phone number, or a phrase you use often.
5) Type in the shortcut you would like to use. For example, “myem” might be for your email address, “800” might be for a phone number, or “tyt” might be for a phrase.
6) Tap Save on the top right.
After you tap Save, you will return to the Text Replacement screen where you should see the shortcut you just added.