How iOS 18 Proofreading Feature Works

Apple's iOS 18 introduces system-wide Writing Tools powered by Apple Intelligence, headlined by an advanced proofreading capability. This feature goes beyond basic spellcheck by analyzing context, syntax, and phrasing to refine written content directly within text fields. This article details how the proofreading feature operates, how users interact with its suggestions, and the underlying technology that powers it across compatible iPhone models.

Accessing the Tool

The proofreading feature is built natively into iOS 18 and functions in virtually any app that supports standard text editing, including Apple Mail, Notes, Messages, and third-party applications. To activate it:

  1. Highlight the text you want to evaluate.
  2. Tap the context menu and select Writing Tools.
  3. Choose the Proofread option.

Contextual Analysis and Processing

Unlike legacy spellcheckers that evaluate words in isolation, the iOS 18 proofreader uses large language models running on-device via Apple Intelligence (or routed securely through Private Cloud Compute for larger requests). The system reads the full sentence or paragraph to understand intent, tone, and grammatical structure.

The tool detects:

  • Grammar and Syntax Errors: Faulty sentence structure, incorrect verb tenses, and subject-verb agreement issues.
  • Spelling and Typos: Misspelled words, repeated words, and context-dependent errors (such as confusing "their" and "there").
  • Punctuation: Missing commas, misused apostrophes, and improper hyphenation.
  • Word Choice: Phrasing that disrupts the flow or clarity of the sentence.

Reviewing and Applying Changes

Once the tool finishes analyzing the selection, it presents the results in an interactive interface rather than automatically overwriting your text:

  • Inline Diff View: The interface highlights suggested modifications, using strikethroughs for removals and distinct colors for additions, allowing you to see exact revisions at a glance.
  • Explanations: Tapping on a highlighted change provides a brief explanation of why the correction was recommended.
  • Granular Control: You can accept all corrections at once with a single tap or review and accept them individually, allowing you to reject changes that alter your intended voice.
  • Original Restoration: If the results do not meet your expectations, an option is provided to revert directly to the original draft.