Native iOS text input

[mazunin-v-jb]

This change introduces an opt-in Native iOS Text Input (NITI) mode for Compose TextField on iOS, enabled via PlatformImeOptions.useNativeInputHandling(enabled) in the iOS source set

With the flag set to true, Compose text fields use UIKit-native text editing and interaction behavior, details in the release notes

Key changes

• Added a new PlatformImeOptions flag: useNativeInputHandling
• Split iOS text input and context menu logic into "NITI vs non-NITI" code paths in:
  • UIKitTextInputService.ios.kt
  • IntermediateTextInputUIView.ios.kt
  • ContextMenu.ios.kt
• When NITI is enabled, Compose-drawn caret and selection handles are suppressed, so UIKit becomes the single source of truth for text controls UI
• Replaced setNeedsRedraw with an explicit draw() call in updateView closure in UIKitTextInputService to eliminate a race condition between UIKit UITextInput queries and TextLayoutResult updates. This could leave iOS with stale text field state, which in NITI mode resulted in incorrect caret positioning and a crash. The fix applies to both NITI and non-NITI scenarios (non-NITI impact was largely not user-visible)
• Implemented selection-aware context menu item updates (caret vs selection):
  • Legacy context menu: updates via LaunchedEffect (through startNotifyingAboutContextMenuItems).
  • New context menu (isNewContextMenu = true): updates via NitiContextMenuUpdaterElement.
• Extracted existing Objective-C helpers into separate files:
  • CMPEditMenuCustomAction
  • CMPTextInputStringTokenizer
• Introduced an additional CMPTextInputView to ensure correct UIKit text input behavior in NITI mode.
• CMPEditMenuView now inherits from CMPTextInputView to unify UIKit text input handling for edit menu interactions

Common code changes

To allow the platform (UIKit) to draw cursor/selection when NITI is enabled, common text field rendering was refactored:

• CoreTextField.kt
  • Introduced platformShouldDrawTextControls (expect) to let the platform decide whether it draws cursor/selection
  • Cursor is shown only when the platform is not drawing it
  • Selection highlight drawing can be suppressed when the platform handles it
• TextFieldDelegate.kt
  • drawHighlight now accepts a drawSelectionHighlight flag and skips selection highlighting when the platform handles drawing
• TextFieldCoreModifier.kt
  • Selection/cursor drawing is delegated to platform-specific drawPlatformSelection / drawPlatformCursor instead of inline drawing

Added API

• UIKitNativeTextInputContext
  • Used to pass required data between ui and foundation modules
• LocalNativeTextInputContext
  • CompositionLocal for accessing UIKitNativeTextInputContext
• PlatformTextInputMethodRequest.textUnclippingOffsetInRoot
  • Used to compute a correct IntermediateTextInputUIView size/position when extra margins are applied and/or when the text field needs to be scrollable

Testing

Manual

1. In a separate project
   Create an expect/actual for KeyboardOptions

Common source set:

@ExperimentalComposeUiApi
expect fun nativeKeyboardOptionsUseNativeInputHandling(enabled: Boolean): KeyboardOptions

iOS source set:

@ExperimentalComposeUiApi
actual fun nativeKeyboardOptionsUseNativeInputHandling(enabled: Boolean): KeyboardOptions {
    return KeyboardOptions(
        platformImeOptions = PlatformImeOptions {
            useNativeInputHandling(enabled)
        }
    )
}

Then use it on any TextField in common code (BasicTextField(TextFieldState) as an example):

BasicTextField(
    state,
    keyboardOptions = nativeKeyboardOptionsUseNativeInputHandling(true)
)

2. In Compose Demo project
   Open Components -> NITI Tests (WIP: coming later)

Automated

• (WIP: coming later)

Release Notes

Features - iOS

• Added an opt-in Native iOS Text Input mode for Compose BasicTextField (both TextFieldValue and TextFieldState) enabled via PlatformImeOptions.useNativeInputHandling(enabled) in iOS source set
• With the native iOS text input flag set to true, BasicTextField uses native UIKit editing and interaction, including:
  • Native caret placement and movement (tap-to-place caret, spacebar caret movement, “ghost caret”)
  • Native magnifier
  • Native selection gestures (double-tap word selection, triple-tap paragraph selection) and iOS-like selection UI (region + handles)
  • Native iOS context menu behavior is supported for both the legacy and the new context menu (isNewContextMenu = true) configurations.
  • Native context menu behavior when interacting with the caret, selection region, or selection handles
  • System iOS text actions in the text field context menu (e.g. Translate, Look Up, Share), provided by UIKit and not available without this mode
  • Autocorrect / typo replacement support
  • Autofill support for text fields, including filling from saved passwords one field at a time
  • Text field controls respect the colors provided by text field theme settings