Can you apply delta time to an SKAction - swift

Question

I've started to notice in the game that I'm making that as the fps goes down as more nodes are on the screen, the nodes start to move with a little choppiness to them. I move the nodes with:
let ran = Int(arc4random_uniform(1400));
let monster = SKSpriteNode(texture: text)
monster.position = CGPoint(x: ran, y: 800);
let move = SKAction.moveTo(CGPointMake(monster.position.x, -100), duration: 2);
let remove = SKAction.runBlock { () -> Void in
score += 1;
monster.removeFromParent()
}
monster.runAction(SKAction.sequence([move,remove]));
Can i use delta time to effect the nodes movements? How do i do this? Would it make any difference?

Answer 1

You cannot do much about your FPS slowing down as you add more nodes to your view. Which device is running your app also determines your FPS. Newer models have a much faster CPU.
To use delta time you can do something like this:
-(void)update:(NSTimeInterval) currentTime {
NSTimeInterval delta = currentTime - self.lastUpdateTime;
self.lastUpdateTime = currentTime;
// use the delta time to determine how much your sprites need to move to stay in sync.
}
If you are looking for a Swift version of the code, look at this previous Q&A here.
You cannot slow down or speed up an SKAction in mid run. To adjust speed of movement you will have to move your node manually by either applying a physics force such as CGVectorMake or by changing its x,y positions.
Add this property:
#property (nonatomic) NSTimeInterval lastUpdateTime;
Then in your update method:
-(void)update:(CFTimeInterval)currentTime {
NSTimeInterval delta = currentTime - self.lastUpdateTime;
self.lastUpdateTime = currentTime;
// sanity check
if(delta > 1)
delta = 0;
float distanceToMovePerSecond = 5.0f;
float numberOfFramesPerSecond = 60.0f;
float xPosition = ((distanceToMovePerSecond/numberOfFramesPerSecond) * delta) * 100;
myNode0.position = CGPointMake(myNode0.position.x+xPosition, myNode0.position.y);
}