This is my GENERAL answer to your question. There are always exceptions.
It sounds like you were given an SOC (Stipulated Order of Continuance) or a CFD (Continuance for Dismissal). Generally, if you abide by the terms of the agreement (you do an evaluation, treatment, stay out of trouble, etc.), at the end of the time period your case will be dismissed. Until then, at least in Spokane, your charge appears as "pending". This means it is not resolved and there has been no disposition entered into the system.
If your applicaiton asks you if you have ever been CONVICTED, and if that is the only thing on your record, generally you can say no. If it asks if you have ever been CHARGED, the answer is yes.
If it has been a year, and the court has dismissed the case, your record will show dismissed, but you will still have a record that you were charged. Whether or not this impacts your ability to be hired depends on the agency's policy on hiring someone with a past CHARGE.
I hope this answers your question. I would always refer you to your paperwork or to the attorney who dealt with your case to verify any further questions.