Recipe: Detecting Misspelling in a UITextView

The UITextChecker class provides a way to automatically scan text for misspellings. To use this class, you must first set the target language—for example, en for English, en_US for U.S. English, fr_CA for Canadian French, and so on. The language codes use a combination of ISO 639-1 and optional ISO 3166-1 regions, so while you can choose to use a general English dictionary (en), you can also differentiate between usage in the U.S. (en_US), Australia (en_AU), and the UK (en_GB). Query UITextChecker for an array of availableLanguages from which to pick.

The class also allows you to learn new words (learnWord:) and forget words (unlearnWord:) to customize the onboard dictionary to the user’s need. Learned words are used globally across languages, so when you add a person’s name, that name is available universally. Checker objects can also set words to ignore using instance methods.