How to Enable Spell Check on an iPhone

Open your iPhone's Settings. It's a gray app with gears pictured that can be found on your Home Screen.

Tap General. It's located in the third group of menu options.

Scroll down and tap Keyboard. It's listed right under Date & Time.

Slide the "Check Spelling" button to the On position. Now your iPhone will underline misspelled words in red when you compose emails and text messages. Spell Check underlines words based on the dictionaries you have enabled on your iPhone. If you find that words that exist are being flagged as misspelled when you type them, you can add those words to your iPhone's dictionary.