How do we enumerate and modify positions array of CCsprite inside Update method?

How do we enumerate and alter our object's position (contained in array) for each delta time?

I put some CCsprite objects inside array, then I displayed them in scene, but also I wanted to make them move with modifying update method, I failed on last part.

How do I get around this ?

  @implementation GameScene

{
    Hunter *_hunter;
    Bird *_bird;

    NSMutableArray *_arrayOfBirds;

   }

-(void)update:(CCTime)delta{

    CGSize viewSize = [CCDirector sharedDirector].viewSize;

    float birdSpeed = 50;

    for (Bird *birds in _arrayOfBirds) {
        if (birds.position.x < 0) {
            birds.flipX = YES;
        }
        if (birds.position.x > viewSize.width) {
            birds.flipX = NO;
        }
        float distanceToMove = birdSpeed * delta;
        float direction = birds.flipX ? 1 : -1;
        float newX = birds.position.x + direction * distanceToMove;
        float newY = birds.position.y;
        birds.position = ccp(newX, newY);
    }
}

-(void)addBird{
    CGSize viewSize = [CCDirector sharedDirector].viewSize;

    for (int i=0; i < 4; i++) {

        _bird = [[Bird alloc]initWithBirdType:(i)];
        _bird.position = ccp(viewSize.width * 0.5f + 30 * i , viewSize.height * 0.9f - 15* i);
        [self addChild:_bird];
        [_arrayOfBirds addObject:_bird];
    }
}

You forgot to initialize your array

here (assuming ARC)

-(id) init {
      if(self=[super init]) {
          _arrayOfBirds = [[NSMutableArray alloc] init]; 
          // the rest
      }
      return self;
}