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Great forms tell users about mistakes as they type, not after they submit. This is live validation, and SwiftUI makes it natural. ✅

Validation reads the same @State string the field writes to. As the value changes, you simply recompute whether it is valid.

Add a computed property that returns true when the input is valid. SwiftUI re-reads it on every keystroke, so it always stays current.

Use an if in the body to reveal a message only when the input is invalid. When the value becomes valid, the hint disappears on its own.

Color speaks faster than words. Tint the hint with foregroundStyle in red so the user instantly notices something needs fixing.

Many rules are about size. Use the count of the string to require a minimum length, like a password of at least eight characters.

Users add stray spaces. Trim them before checking so an entry of only spaces does not slip through as valid by mistake.

Tie the submit Button to your check with the disabled modifier. While the input is invalid, the button simply cannot be tapped.

Need to run code on each edit? The onChange modifier fires whenever the value changes, perfect for logging or extra checks.

You never manually refresh anything. Because validation reads state, every keystroke recomputes the hints and button for free.

Live validation turns frustration into guidance. Clear hints and a smart submit button make your form feel helpful, not strict. ✨

You built live validation from a computed check, showed colored hints, trimmed input, and disabled the button until everything was valid. 🎉