ios - Why is the currentData in my Firebase transaction always nil?

Question

This is how the DB presented over Firebase

Parent
      Match
           User 1
                 Opponent : User 2
                 State    : "NotReady"
           User 2 
                 Opponent : User 1
                 State    : "NotReady"

I'm trying to update the values of State (each user individually) with RunTransaction.

What I was trying to do :

• Check that the item haven't removed(is not nil/null)
• If he is exist - update the value
• if he doesnt exists - manipulate UI

• if he suddenly deleted - abort the transaction (Possible condition - if two close event running at the same time, one updating "State" and other deletes the all key(removeValue)

   let path =  "Parent/Match/User 1/state"
  
   let futureRef = Firebase(url: path)
           futureRef.runTransactionBlock({
      (currentData:FMutableData!) in
      let value = currentData.value as? String
  
      if value != nil  {
          currentData.value = "Ready"
  
          return FTransactionResult.successWithValue(currentData)
      }
  
          return FTransactionResult.abort()
  
      }, andCompletionBlock: {
          // Completion Check
          (error:NSError!, success:Bool, data:FDataSnapshot!) in
  
          if error == nil && success && data.value as! String == "Ready"
          {
              //Value is not null(not removed) and he is ready
                ManipulateUI()
  
          }
          else 
        {
  
          //Value deleted
         }
  
  
          }
      )
  

But for some reason - I'm getting currentData that is nil and going straight to the Abort. Any suggestions? Thanks!!!

Answer 1

Waitting for answers