Apple Game Frameworks and Technologies

Use Constraints to Limit Movement

At the moment, the player node moves to the tap location instead of staying on the platform. There’s a way to fix this problem using constraints and the SKConstraint class.

With constraints, you can restrict a node’s movement to a specific area. In this case, you need to limit the player.position.y value to keep Blob firmly on the platform.

Open the Player.swift file and add a new method above the walk() method:

func setupConstraints(floor: CGFloat) {
  let range = SKRange(lowerLimit: floor, upperLimit: floor)
  let lockToPlatform = SKConstraint.positionY(range)

  constraints = [ lockToPlatform ]
}

This new method sets up a range with an upper and lower limit using the values you pass in ...