Stopping nodes to exact positions - objective-c

Question

I have a node moving on the screen with a velocity of 400pps. I would like to stop the node when it reaches a precise location on the screen. I am doing so by setting the node velocity to 0 in the update cycle.
However, the node moves pass the desired point by an unpredictable amount, and stops somewhere later.
I suspect the problem is in the response time. Simply put, the physic engine is not quick enough to stop the node accurately. My app is running at 30fps on my Mac and 60fps on iPhone 5S.
What is the best way to achieve accurate node movements and stopping? I suppose I could reposition the node to the desired location after I stop it, but that would probably mess up the all physic world.
This is how the relevant part of my update method looks like:
- (void)update:(NSTimeInterval)currentTime {
// Start moving
if(verticalScrollSpeed) {
node.physicsBody.velocity = CGVectorMake(0, verticalScrollSpeed);
}
// Stop moving
if(verticalScrollSpeed > 0 && obstaclesContainerNode.position.y >= 0) {
verticalScrollSpeed = 0;
node.physicsBody.velocity = CGVectorMake(0, 0);
}
}

Answer 1

You would have to cheat a little. Nothing is really "moving" in a game. everything is just kinda teleporting however many pixels per frame. If something is moving extremely fast you may overshoot. The best you can do is something like this
if distanceToTarget <= 1 {
yourNode.position = targetNode.position
}
The other thing you can consider is slowing down your node as it gets closer to the other one. That would make arrival more accurate.. but that may or may not be something you want for your game.