How to wait for iSpeech to finish speaking before passing the next string

Question

Im using iSpeech API. I've posted in their forums but there is not much activity over there. I can pass it a string and have the app speak it. But now I want to pass in an array of strings, say 5. I want the engine to speak those strings one after the other but it only speaks the first one. I decided to use NSOperationQueue so in my viewDidLoad I did:

//Create Queue
    queue = [[NSOperationQueue alloc] init];
    [queue setMaxConcurrentOperationCount:1];

And then later I do this:

• (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{

  //Set loop for 5 strings
  [self fetchStringsToSpeak:indexPath];
  

  }

  -(void)fetchStringsToSpeak:(NSIndexPath*)indexPath{

  int stringsToSpeak = 5;
  
  for (int counter = 0; counter < stringsToSpeak; counter++) {
  
      //Get the string
      NSDictionary *currentString = [self.stringsArray objectAtIndex:indexPath.row+counter];
  
      //3. Fill im text and image for cell
      NSString *string = [currentString objectForKey:@"text"];
  
      //Clean the string from URLs
      NSError *error;
      NSDataDetector *linkDetector = [NSDataDetector dataDetectorWithTypes:NSTextCheckingTypeLink error:&error];
      NSArray *matches = [linkDetector matchesInString:string options:0 range:NSMakeRange(0, [string length])];
      NSLog(@"matches %@", matches);
  
      if ([matches count] > 0) {
          for (NSTextCheckingResult *match in matches) {
              if ([match resultType] == NSTextCheckingTypeLink) {
                  NSString *linkToRemove = [[match URL] absoluteString];
                  self.cleanString = [string stringByReplacingOccurrencesOfString:linkToRemove withString:@""];
                  NSLog(@"Clean string: %@", self.cleanString);
  
              }
          }
      } else {
          NSLog(@"NO LINK");
          self.cleanString = string;
      } //END IF/ELSE
  
  NSInvocationOperation *operation = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(speakAString:) object:self.cleanString];
  [queue addOperation:operation];
  
  //Message back to the main thread
  [self performSelectorOnMainThread:@selector(taDah) withObject:nil waitUntilDone:YES];
  
  } //END FOR LOOP
  

  }

  • (void)speakAString:(NSString*)stringToSpeak { ISSpeechSynthesis *synthesis = [[ISSpeechSynthesis alloc] initWithText:stringToSpeak]; NSError *err; if(![synthesis speak:&err]) { NSLog(@"ERROR: %@", err); } self.cleanString = nil; }

It is passed the values by these methods:

It speaks the first one but then I get this:

Domain=com.ispeech.ispeechsdk.ErrorDomain Code=303 "The SDK is already performing synthesis or recognition. Wait for that to finish before starting another request." UserInfo=0xb54f2b0 {NSLocalizedDescription=The SDK is already performing synthesis or recognition. Wait for that to finish before starting another request.}

Why is the operation queue not waiting?