How can I match up some code and an animation keyframe

Hi all,

Basically I have a script which parses some text and reveals a character from the string every x seconds to give the effect of text being printed out. I also have a portrait sprite which is placed next to the text as it is printed.

The portrait sprite is controlled using the animation editor in unity to turn the sprite on/off at a timed keyframe.

sprite render = true at 3 seconds as the text script is enabled

sprite render = false at 20 seconds as the text script finishes

Now the problem seems to be that the text script can take a varying amount of time to complete which makes it impossible to turn the sprite off at the correct time.

I know I could access the portrait sprite object from within the code and turn it off manually, but there is potentially multiple sprites all turning off at different times and I would rather leave this side to the designer of the scene

Anyone have any ideas how to fix this?

Added a rough idea of how the code works below.

 void FixedUpdate () 
 {
     if (Active)
     {
         StartCoroutine( AnimateText(text) );
         Active = false;
     }
 }

 IEnumerator AnimateText(string strComplete)
 {
         while( i < strComplete.Length )
         {
             bool found = false;
             bool done = false;
             char newchar = strComplete[i];
                 
             while( !found )
             {
                 newchar = strComplete[i];
                     
                 switch (newchar)
                 {
                     default: found = true; break;
                 }
             }
                 
         if (!done)
         {
             font.text += newchar;
             i++;
             yield return new WaitForSeconds(TextSpeed);
         }
     }