손목 받아쓰기: 빈 목록 말고 nil, 그리고 위로 쓸기

import WatchKit

/// Dictation on watchOS goes through WatchKit. SwiftUI's dictation controls are unavailable here,
/// and there is no Speech framework on the watch.
enum WristDictation {
    /// nil suggestions opens the microphone at once. An EMPTY array would show the input list instead.
    /// The language switch is a swipe up on the dictation screen itself; the app adds no second door.
    @MainActor
    static func speak(_ deliver: @escaping @MainActor @Sendable (String?) -> Void) -> Bool {
        // nil until a view is on screen: a cold launch from the Action Button can land here too early.
        guard let controller = WKApplication.shared().visibleInterfaceController else { return false }
        controller.presentTextInputController(withSuggestions: nil, allowedInputMode: .plain,
                                              completion: completion(deliver))
        return true
    }

    /// Built off any actor. An inline closure written in a @MainActor method would inherit that
    /// isolation, and WatchKit may call it elsewhere.
    nonisolated static func completion(_ deliver: @escaping @MainActor @Sendable (String?) -> Void)
        -> @Sendable ([Any]?) -> Void {
        { results in
            let text = (results?.first as? String)?.trimmingCharacters(in: .whitespacesAndNewlines)
            Task { @MainActor in deliver(text?.isEmpty == false ? text : nil) }
        }
    }
}

# What the watchOS SDK actually offers, checked against the installed SDK rather than memory.
WSDK=$(xcrun --sdk watchsimulator --show-sdk-path)

# SwiftUI's dictation controls: declared unavailable on watchOS.
grep -h -B3 'struct TextInputDictationBehavior' \
  "$WSDK"/System/Library/Frameworks/SwiftUI.framework/Modules/SwiftUI.swiftmodule/*.swiftinterface | head -4
#   @available(watchOS, unavailable)

# No Speech framework on the watch, so no recognizer with an app-chosen locale.
ls "$WSDK/System/Library/Frameworks" | grep -c '^Speech.framework'          # 0

# The language-choosing variant exists and imports into Swift, but its header says it
# "will never go straight to dictation".
grep -o 'will never go straight to dictation[^;]*' \
  "$WSDK/System/Library/Frameworks/WatchKit.framework/Headers/WKInterfaceController.h"