How to use NSMutable Array with Struct - Xcode

I am using an NSMutableArray to store a struct with data. So I am having problem to get values from NSMutableArray/Struct. Take a look in my code below: ....

{

     NSMutableArray * arrGameControl;
     arrGameControl = [NSMutableArray array];

     //Struct definition
     typedef struct {
      int player; 
      int armaCod;
      int armaID;
      int armaIndex;
      int armaIndexStatus;
      int armaIdOrientacao;
     } sttDataGame;

     //Define the valDados and put values inside struct
     sttDataGame valDados;

     valDados.armaCod=30;
     valDados.armaID=30;
     valDados.armaIdOrientacao=30;
     valDados.armaIndex=30;
     valDados.armaIndexStatus=30;
     valDados.player=30;

     NSLog(@"Valor Inicial :  %d",
        valDados.armaCod);

     //Add rows in my NSMutableArray using struct data
     [ arrGameControl addObject: [NSValue value:&valDados withObjCType:@encode(struct sttDataGame)]];

     //Reset struct values
     valDados.armaCod=0;

     //Here I have a problem
     [[ arrGameControl objectAtIndex:0] getValue:&valDados];

     NSLog(@"%d",valDados.armaCod);

}

..............

What's wrong in this code? Thanks for your attention.