Scoring
Keeping Score
Lets add a score system to the game. We’ll do a simple time based score, you’ll get points for staying alive.
We need a variable to store the score and a label to display the score on the screen.
We can add a label to the scene as shown below/.
class GameScene: SKScene, SKPhysicsContactDelegate {
// creates a SKLabelNode using the given font
let scoreLabel = SKLabelNode(fontNamed: "AvenirNextCondensed-Bold")
override func didMove(to view: SKView)
{
scoreLabel.zPosition = 2
scoreLabel.position.y = (self.frame.size.height - 50)
addChild(scoreLabel)
}
}
Next we add a variable to hold the score and use a feature of Swift that allows us to attach an observer to a variable. In this case we set an observer on score that changes the scoreLabel text when score changes.
class GameScene: SKScene, SKPhysicsContactDelegate {
// creates a SKLabelNode using the given font
let scoreLabel = SKLabelNode(fontNamed: "AvenirNextCondensed-Bold")
var score = 0 {
didSet {
scoreLabel.text = "SCORE: \(score)"
}
}
override func didMove(to view: SKView)
{
scoreLabel.zPosition = 2
scoreLabel.position.y = (self.frame.size.height - 50)
addChild(scoreLabel)
// we "change" score to 0 to force the label to update and display
score = 0
}
}
Finally we increment the score in the update.
override func update(_ currentTime: TimeInterval) {
if player.parent != nil {
score += 1
}
}