fix(ios): non-continuous recognition timers

Author: jamsch

ios/ExpoSpeechRecognizer.swift

@@ -286,8 +286,8 @@ actor ExpoSpeechRecognizer: ObservableObject {
         )
       }
 
-      // Don't run any timers if the audio source is from a file
-      let continuous = options.continuous || isSourcedFromFile
+      // Run timers on non-continuous mode, as long as the audio source is the mic
+      let shouldRunTimers = !options.continuous && !isSourcedFromFile
       let audioEngine = self.audioEngine
 
       self.task = recognizer.recognitionTask(
@@ -300,18 +300,20 @@ actor ExpoSpeechRecognizer: ObservableObject {
             }
           }
 
-          // Result handler
+          // Handle the result
           self?.recognitionHandler(
             audioEngine: audioEngine,
             result: result,
             error: error,
             resultHandler: resultHandler,
             errorHandler: errorHandler,
-            continuous: continuous
+            continuous: options.continuous,
+            shouldRunTimers: shouldRunTimers,
+            canEmitInterimResults: options.interimResults
           )
         })
 
-      if !continuous {
+      if shouldRunTimers {
         invalidateAndScheduleTimer()
       }
 
@@ -449,7 +451,10 @@ actor ExpoSpeechRecognizer: ObservableObject {
       request = SFSpeechAudioBufferRecognitionRequest()
     }
 
-    request.shouldReportPartialResults = options.interimResults
+    // We also force-enable partial results on non-continuous mode,
+    // which will allow us to re-schedule timers when text is detected
+    // These won't get emitted to the user, however
+    request.shouldReportPartialResults = options.interimResults || options.continuous
 
     if recognizer.supportsOnDeviceRecognition {
       request.requiresOnDeviceRecognition = options.requiresOnDeviceRecognition
@@ -613,12 +618,25 @@ actor ExpoSpeechRecognizer: ObservableObject {
     error: Error?,
     resultHandler: @escaping (SFSpeechRecognitionResult) -> Void,
     errorHandler: @escaping (Error) -> Void,
-    continuous: Bool
+    continuous: Bool,
+    shouldRunTimers: Bool,
+    canEmitInterimResults: Bool
   ) {
+    // When a final result is returned, we should expect the task to be idle or stopping
     let receivedFinalResult = result?.isFinal ?? false
     let receivedError = error != nil
 
-    if let result: SFSpeechRecognitionResult {
+    // Hack for iOS 18 to detect final results
+    // See: https://forums.developer.apple.com/forums/thread/762952 for more info
+    // This can be emitted multiple times during a continuous session, unlike `result.isFinal` which is only emitted once
+    var receivedFinalLikeResult: Bool = receivedFinalResult
+    if #available(iOS 18.0, *), !receivedFinalLikeResult {
+      receivedFinalLikeResult = result?.speechRecognitionMetadata?.speechDuration ?? 0 > 0
+    }
+
+    let shouldEmitResult = receivedFinalResult || canEmitInterimResults || receivedFinalLikeResult
+
+    if let result: SFSpeechRecognitionResult, shouldEmitResult {
       Task { @MainActor in
         let taskState = await task?.state
         // Make sure the task is running before emitting the result
@@ -638,15 +656,16 @@ actor ExpoSpeechRecognizer: ObservableObject {
       }
     }
 
-    if receivedFinalResult || receivedError {
+    if (receivedFinalLikeResult && !continuous) || receivedError || receivedFinalResult {
       Task { @MainActor in
         await reset()
       }
+      return
     }
 
     // Non-continuous speech recognition
     // Stop the speech recognizer if the timer fires after not receiving a result for 3 seconds
-    if !continuous && !receivedError {
+    if shouldRunTimers && !receivedError {
       invalidateAndScheduleTimer()
     }
   }