UpdateTimer is a simple struct that tracks commonly-needed chronological variables in the scene loop of a game. It currently exposes:

• Time since last update
• Time since first update
• Total frame count (number of times update() has been called)

lap timer

UpdateTimer also includes a lap timer that makes it trivial to track an arbitrary event (i.e., one that doesn't necessarily happen every update() cycle). During your scene loop's update() method, timeSinceLastLap will be set to the number of seconds since the previous time lap() was called (or, if it has never been called, the number of seconds since the first call to update()). Call lap() any time the event you're monitoring occurs, and timeSinceLastLap will reset to 0 and begin counting up again.

class MyScene: SKScene
{
    let spawnMonsterInterval: NSTimeInterval = 5
    private var updateTimer = UpdateTimer()

    func update(currentTime:NSTimeInterval) {
        updateTimer.update(currentTime)

        println("seconds since last update() = \(updateTimer.timeSinceLastUpdate)")
        println("seconds since first update() = \(updateTimer.timeSinceFirstUpdate)")
        println("seconds since monster was spawned = \(updateTimer.timeSinceLastLap)")
        println("number of times update() has been called = \(updateTimer.frameCount)")

        if updateTimer.timeSinceLastLap >= spawnMonsterInterval {
            spawnMonster()
            updateTimer.lap()           // resets `timeSinceLastLap` to zero
        }
    }
}

authors / contributors

bryn austin bellomy < [email protected] >