Much of the remaining functionality is in the
update method. There are three distinct sections of the loop, and we will look at them in turn. The first section handles the movement updates.
Filename: SNPlayfieldLayer.m (update, part 1)
-(void)update:(ccTime)dt {
stepTime += dt;
if (stepTime > snake.snakeSpeed) {
stepTime = 0;
[snake move];
[self checkForCollisions];
}We use a standard delta time counter to keep adding to the
stepTime variable. On each loop, we check if the stepTime is greater than the snakeSpeed variable. If it is, then we need to move the snake. As discussed in the previous sections of the chapter, all we have to do is call the snake's move method. The only time we need to check for collisions is after the snake's move method is called, so we call that method next.