การผูก TextField กับสถานะ

A TextField is SwiftUI's box where users type. Give it a prompt and somewhere to store what they enter, and you have live text input. ✍️

Typed characters must go somewhere. You store them in a @State string that the text field reads from and writes to as the user types.

A TextField needs a two-way link called a binding. It both reads the current value and writes new keystrokes back into your state.

To pass a binding, prefix the property with $. Writing $name hands the text field a two-way connection instead of a plain copy.

The first argument is the placeholder: faint hint text shown when the field is empty. It disappears the moment the user starts typing.

Because the field writes into your state, you can read name anywhere in the body to react to what the user has typed so far.

Add the textFieldStyle modifier with .roundedBorder to give the field a clean, tappable outline instead of a bare line.

You never write code to refresh the screen. When the binding changes the state, SwiftUI re-renders the view automatically for you. ✨

The @State string is the single source of truth. The field and any Text that reads it always stay perfectly in sync.

Writing name passes a read-only copy. Writing $name passes the binding the field needs to send edits back. The dollar sign matters.

A state string, a TextField bound with $, and a Text that reads it: that is a complete, reactive input screen.

You bound a TextField to @State with the $ prefix, so typing updates your value and the UI refreshes itself. That is reactive input in a nutshell. 🎉